Add build info on Mac

.. see src/mac/Info.plist.app, based upon the default for
   Mac with clang found in mkspecs/default/Info.plist.app
   from the Qt installation directories.

.. we make our own to add build version information, which
   should be placed there via the qmake 'VERSION' macro but
   its not supported -- you have to edit the plist file instead.

Fixes #796

src/mac/Info.plist.app

@@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>NSPrincipalClass</key>
+	<string>NSApplication</string>
+	<key>CFBundleIconFile</key>
+	<string>@ICON@</string>
+	<key>CFBundlePackageType</key>
+	<string>APPL</string>
+	<key>CFBundleGetInfoString</key>
+	<string>3.1.0 (developer)</string>
+	<key>CFBundleSignature</key>
+	<string>@TYPEINFO@</string>
+	<key>CFBundleExecutable</key>
+	<string>@EXECUTABLE@</string>
+	<key>CFBundleIdentifier</key>
+	<string>@BUNDLEIDENTIFIER@</string>
+	<key>NOTE</key>
+	<string>3.1.0 pre-release</string>
+</dict>
+</plist>

src/src.pro

@@ -9,6 +9,7 @@ TEMPLATE = app
 TARGET = GoldenCheetah
 !isEmpty( APP_NAME ) { TARGET = $${APP_NAME} }
 DEPENDPATH += .
+QMAKE_INFO_PLIST = ./mac/Info.plist.app
 
 ## qwt and libz
 INCLUDEPATH += ../qwt/src ../qxt/src $${LIBZ_INCLUDE}