Restructure source directory

Introducing a directory structure to make it a bit less
daunting for new developers and perhaps even old hands.

The main folders all start with an upper character, so src
files are now located in;

* Core - Core data structures
* Gui - Main GUI elements
* Metrics - Models and Metrics
* FileIO - Device and File I/O
* Charts - All the chart types
* Cloud - Working with Web Resources
* Train - Anything Train View specific
* ANT - Our ANT+ Stack
* Resources - Images, Translations, Web etc

Apologies to anyone who needs to merge across this update.

doc/user/style.txt

@@ -0,0 +1,33 @@
+
+                    GoldenCheetah Coding Style Guidelines
+
+I don't like coding conventions, and I would prefer GoldenCheetah had as few
+of them as possible.  The ones below, however, seem prudent.  Please follow
+them when possible.  -- Sean
+
+- Use spaces instead of tabs.
+
+- Do not end lines with whitespace.  End every file with a newline.
+  Otherwise git becomes angry.
+
+- Avoid "using namespace ..." in header files.
+
+- Don't declare global variables in header files.  If you must use a global
+  variable, declare it "static" withing a .cpp file.
+
+- Only call C++'s operator new within the constructors and reset() functions
+  of std::auto_ptr, boost::scoped_pointer, etc. or when passing a parent
+  pointer to a Qt class (so that the parent deletes the child).  Never call
+  delete explicitly.
+
+- Do not use malloc or free unless forced to by an external C library.
+
+- Allocate large buffers on the heap, not on the stack.
+
+- When the C++ standard library has an appropriate function, use it.
+  Likewise for Qt and Boost.
+
+- Only use external libraries with GPL-compatible licenses.
+
+- Avoid C-style casts.
+