Fixed ES3 build.
Added NV_fbo_color_attachments ES extension to the list.
Shader-related limit queries.

Renamed AbstractShaderProgram::maxSupportedVertexAttributeCount() to
maxVertexAttributes(), the old function is now an alias to retain
source compatibility, will be removed in future release.

Also printing the values in magnum-info.
Mesh-related limit queries.

Also printing the values in magnum-info.
Framebuffer-related limit queries.

Also printing the values in magnum-info.
Buffer-related limit queries.

Also printing the values in magnum-info.
Texture-related limit queries.

Renamed AbstractTexture::maxSupportedLayerCount() to maxLayers(),
which is in fact alias to Shader::maxCombinedTextureImageUnits(). Also
renamed Samples::maxSupportedAnisotropy() to maxAnisotropy(). It now
has slightly confusing naming, will fix that later. Both
original functions are now alias to new ones to retain source
compatibility, will be removed in future releases.

Also printing the values in magnum-info.
Mention that line/polygon smooth and compiler query is not supported.
Add some TODOs for remaining limit queries.
Renamed ImageType and ImageFormat to ColorType and ColorFormat.

Makes more sense. Added aliases and header file for backwards
compatibility, will be removed in future versions.
Platform: ability to not print all those implementation-defined values.