Added .gitignore
Removed missing includes from main header files
Merge remote-tracking branch 'upstream/master'
constexpr in Vec2, Vec3 and Angle now preserves behaviour with C++14
Angle::Atan2, Angle::Asin and Angle::Acos are no longer constexpr

I changed that because it seems that std::atan2, std::acos and std::asin
are only constexpr when compiling with GCC.
Merge remote-tracking branch 'upstream/master'
Compiling now working with clang 3.3. SST::decorateVal() still fails
Added debugging functions
Image will now write warning messages in case of invalid textures
Added resource loading logging
Added error message in case of failed glGenTextures
The OpenGL context version is now specified
Removed glDisable(GL_DEPTH) because it caused a GL_INVALID_ENUM error
Emscripten doesn't support constexpr for any std function
Building with emscripten now works. Running my temporary test project with emscripten not.
Removed DataType from ResourceManager::Data
Fixed tabs.
SDL now uses attributes and vsync
SDL now obeys the NoVSync flag
Removed comparison against a string literal

Clang said it would be unspecified. So I removed it.