Move contributed sources to contrib directory

.. Makes it easier to identify code that has been snaffled in from
   other repositories and check licensing

.. The httpserver is now no longer optional, since it is delivered
   as contributed source.

src/src.pro

@@ -6,6 +6,9 @@
 ###############################################################################
 
 !versionAtLeast(QT_VERSION, 5.13):error("Use at least Qt version 5.13")
+greaterThan(QT_MAJOR_VERSION, 5) {
+    error("Qt6 is unsupported whilst we wait for key dependencies to be included.")
+}
 
 ###==========================
 ### IMPORT USER CONFIGURATION
@@ -53,7 +56,8 @@ QMAKE_CFLAGS_ISYSTEM =
 ###=======================================================================
 
 # qwt, qxt, libz, json, lmfit and qwtcurve
-INCLUDEPATH += ../qwt/src ../qxt/src ../qtsolutions/json ../qtsolutions/qwtcurve ../lmfit ../levmar
+INCLUDEPATH += ../qwt/src ../contrib/qxt/src ../contrib/qtsolutions/json \
+               ../contrib/qtsolutions/qwtcurve ../contrib/lmfit ../contrib/levmar
 DEFINES += QXT_STATIC
 
 # to make sure we are toolchain neutral we NEVER refer to a lib
@@ -174,8 +178,8 @@ macx {
 }
 
 #### these are no longer non-mac only
-HEADERS += ../qtsolutions/segmentcontrol/qtsegmentcontrol.h
-SOURCES += ../qtsolutions/segmentcontrol/qtsegmentcontrol.cpp
+HEADERS += ../contrib/qtsolutions/segmentcontrol/qtsegmentcontrol.h
+SOURCES += ../contrib/qtsolutions/segmentcontrol/qtsegmentcontrol.cpp
 
 # X11
 if (defined(GC_WANT_X11)) {
@@ -498,20 +502,19 @@ contains(DEFINES, "GC_WANT_R") {
 
 
 ###==================================
-### OPTIONAL => HTTP API WEB SERVICES
+### HTTP API WEB SERVICES
 ###==================================
 
-!isEmpty (HTPATH) {
+HTPATH = ../contrib/httpserver
+INCLUDEPATH += $$HTPATH
+DEPENDPATH += $$HTPATH
 
-    INCLUDEPATH += $$HTPATH
-    DEPENDPATH += $$HTPATH
+DEFINES += GC_WANT_HTTP
 
-    DEFINES += GC_WANT_HTTP
+HEADERS +=  Core/APIWebService.h
+SOURCES +=  Core/APIWebService.cpp
 
-    HEADERS +=  Core/APIWebService.h
-    SOURCES +=  Core/APIWebService.cpp
-
-    HEADERS +=  $$HTPATH/httpglobal.h \
+HEADERS +=  $$HTPATH/httpglobal.h \
             $$HTPATH/httplistener.h \
             $$HTPATH/httpconnectionhandler.h \
             $$HTPATH/httpconnectionhandlerpool.h \
@@ -522,7 +525,7 @@ contains(DEFINES, "GC_WANT_R") {
             $$HTPATH/httpsession.h \
             $$HTPATH/httpsessionstore.h \
             $$HTPATH/staticfilecontroller.h
-    SOURCES +=  $$HTPATH/httpglobal.cpp \
+SOURCES +=  $$HTPATH/httpglobal.cpp \
             $$HTPATH/httplistener.cpp \
             $$HTPATH/httpconnectionhandler.cpp \
             $$HTPATH/httpconnectionhandlerpool.cpp \
@@ -533,7 +536,6 @@ contains(DEFINES, "GC_WANT_R") {
             $$HTPATH/httpsession.cpp \
             $$HTPATH/httpsessionstore.cpp \
             $$HTPATH/staticfilecontroller.cpp
-}
 
 
 ###=====================================================
@@ -739,10 +741,12 @@ HEADERS += Metrics/Banister.h Metrics/CPSolver.h Metrics/Estimator.h Metrics/Ext
 HEADERS += Planning/PlanningWindow.h
 
 # contrib
-HEADERS += ../qtsolutions/codeeditor/codeeditor.h ../qtsolutions/json/mvjson.h ../qtsolutions/qwtcurve/qwt_plot_gapped_curve.h \
-           ../qxt/src/qxtspanslider.h ../qxt/src/qxtspanslider_p.h ../qxt/src/qxtstringspinbox.h ../qzip/zipreader.h \
-           ../qzip/zipwriter.h ../lmfit/lmcurve.h  ../lmfit/lmcurve_tyd.h  ../lmfit/lmmin.h  ../lmfit/lmstruct.h \
-           ../levmar/compiler.h  ../levmar/levmar.h  ../levmar/lm.h  ../levmar/misc.h
+HEADERS += ../contrib/qtsolutions/codeeditor/codeeditor.h ../contrib/qtsolutions/json/mvjson.h \
+           ../contrib/qtsolutions/qwtcurve/qwt_plot_gapped_curve.h  ../contrib/qxt/src/qxtspanslider.h \
+           ../contrib/qxt/src/qxtspanslider_p.h ../contrib/qxt/src/qxtstringspinbox.h ../contrib/qzip/zipreader.h \
+           ../contrib/qzip/zipwriter.h ../contrib/lmfit/lmcurve.h  ../contrib/lmfit/lmcurve_tyd.h \
+           ../contrib/lmfit/lmmin.h  ../contrib/lmfit/lmstruct.h \
+           ../contrib/levmar/compiler.h  ../contrib/levmar/levmar.h  ../contrib/levmar/lm.h  ../contrib/levmar/misc.h
 
 # Train View
 HEADERS += Train/AddDeviceWizard.h Train/CalibrationData.h Train/ComputrainerController.h Train/Computrainer.h Train/DeviceConfiguration.h \
@@ -840,13 +844,14 @@ SOURCES += Metrics/aBikeScore.cpp Metrics/aCoggan.cpp Metrics/AerobicDecoupling.
 SOURCES += Planning/PlanningWindow.cpp
 
 ## Contributed solutions
-SOURCES += ../qtsolutions/codeeditor/codeeditor.cpp ../qtsolutions/json/mvjson.cpp ../qtsolutions/qwtcurve/qwt_plot_gapped_curve.cpp \
-           ../qxt/src/qxtspanslider.cpp ../qxt/src/qxtstringspinbox.cpp ../qzip/zip.cpp \
-           ../lmfit/lmcurve.c ../lmfit/lmmin.c \
-           ../levmar/Axb.c ../levmar/lm_core.c ../levmar/lmbc_core.c \
-           ../levmar/lmblec_core.c ../levmar/lmbleic_core.c ../levmar/lmlec.c ../levmar/misc.c \
-           ../levmar/Axb_core.c ../levmar/lm.c ../levmar/lmbc.c ../levmar/lmblec.c ../levmar/lmbleic.c \
-           ../levmar/lmlec_core.c ../levmar/misc_core.c
+SOURCES += ../contrib/qtsolutions/codeeditor/codeeditor.cpp ../contrib/qtsolutions/json/mvjson.cpp \
+           ../contrib/qtsolutions/qwtcurve/qwt_plot_gapped_curve.cpp \
+           ../contrib/qxt/src/qxtspanslider.cpp ../contrib/qxt/src/qxtstringspinbox.cpp ../contrib/qzip/zip.cpp \
+           ../contrib/lmfit/lmcurve.c ../contrib/lmfit/lmmin.c \
+           ../contrib/levmar/Axb.c ../contrib/levmar/lm_core.c ../contrib/levmar/lmbc_core.c \
+           ../contrib/levmar/lmblec_core.c ../contrib/levmar/lmbleic_core.c ../contrib/levmar/lmlec.c ../contrib/levmar/misc.c \
+           ../contrib/levmar/Axb_core.c ../contrib/levmar/lm.c ../contrib/levmar/lmbc.c ../contrib/levmar/lmblec.c ../contrib/levmar/lmbleic.c \
+           ../contrib/levmar/lmlec_core.c ../contrib/levmar/misc_core.c
 
 ## Train View Components
 SOURCES += Train/AddDeviceWizard.cpp Train/CalibrationData.cpp Train/ComputrainerController.cpp Train/Computrainer.cpp Train/DeviceConfiguration.cpp \