improved OpenGL ES support

include/ACGL/ACGL.hh

include/ACGL/Base/CompileTimeSettings.hh

include/ACGL/Base/OSDetection.hh

include/ACGL/OpenGL/Debug.hh

include/ACGL/OpenGL/GL.hh

include/ACGL/OpenGL/Objects/Buffer.hh

include/ACGL/OpenGL/Objects/Query.hh

include/ACGL/OpenGL/Objects/Shader.hh

include/ACGL/OpenGL/Objects/ShaderProgram.hh

include/ACGL/Utils/FileHelpers.hh

include/ACGL/Utils/FileHelpersiOS.h

src/ACGL/ACGL.cc

src/ACGL/OpenGL/Creator/ShaderParser.cc

src/ACGL/OpenGL/Debug.cc

src/ACGL/OpenGL/Objects/Texture.cc

src/ACGL/OpenGL/Objects/VertexArrayObject.cc

src/ACGL/OpenGL/Tools.cc

src/ACGL/Utils/FileHelpers.cc

src/ACGL/Utils/FileHelpersiOS.mm