Bug fix!

Text should be copyable.
Added color class. And added license.
Text uses utf8 strings to dispay text.
The openGl bind texture is now const.

And so is the draw function in the corresponding classes.

Textures is now only saved in graphic memory.
Critical bug fix! To texture.

Width and height used null pointer and image loading always faild. This
should now be fixed.
Implements wrapper around usage of joystick.
protected functions now public.
Fixed critical error in Font.

The internal font never returned! And made the Text class better. The
text width is now calculated at the text creation instead at the first
draw.
Critical bug fix! Risk of null pointer used!
Bug fix to Text.

size was incorrectly set when text was set to the same text.
Bug fix in Text.

Default size set to zero.
Text sometimes not displayed!
Fixed CMakeLists.
Release version is now working in Visual Studio.
Texture constructor was not implemented!

Fixed!
Removed one of the constructor in Texture.
Update FindSDL2.cmake.

Some linux distros failes if SDL2MAIN.lib is used. Only Windows uses
SDL2MAIN.lib.
Fixed gcc compilation error.
Updated the cmake file.

Removed visual studio warnings. Changed to lowercaser.
Updated the cmake file.