Merge pull request #70 from dariomanesku/master

Small refactor.
SDL: Fixed clang warnings.
Use aligned allocator for context.
Pass precision qualifier from varying.def.sc to shader.
Updated shaderc linux executable.
Updated windows shaderc executable.
Write GLSL shader #version before compiling shader.
Added MRT support.
Added destroy shaders option when creating program.
shaderc: Improved error output. Added code preprocessing before substituting code.
shaderc: Updated linux binary.
shaderc: Added ARB_shader_texture_lod extension.
Merge branch 'master' of github.com:bkaradzic/bgfx
shaderc: Updated Linux binary.
Removed tools executables to avoid repo bloat, and stale executables. Added makefile rule to build tools.
.
Fixed makefile.
Cleanup.
Updated copyright year.
Updated copyright year.