Most input and GUI files are now in a common ui/ directory. The platform/
directory is no longer, as everythyng was moved to application/ or ui/.

In particular, get rid of the enum magic; we can use map<string,int> if we
really need some named enums. Which we usually don’t.

sdl integration now supports OS character input as per existing in sdl.
Use SetTextInputActive to turn it off/on

The containers no longer force the user to use the ptrdiff_t type for
size information. For convenience, size() now always returns an int,
and the size_s() method offers a way to handle arrays with more than
2 billion elements. Internally, we still use ptrdiff_t, though.

Since so much code had to be changed, I took the opportunity to get
rid of capitalised accessors for classes that are lowercase.

MeshViewer first pass

SDL2: Mouse is back ! With correct focus support
SDL2: Added typing support with keyboard
ShaderBuilder: Refactored and simplified Shader block creation
Several warning removal
Fixed Image::Copy

and 2) fuck the Visual Studio compiler that crashes when confused.

Constants : Added minus one.

- fixed 1270 CR characters
 - fixed 56 trailing spaces
 - fixed 5085 tabs

Added BulletCharacterController.cpp & BulletCharacterController.h stubs.