renamed sgl::Model to sgl::Mesh
added functions to generate basic mesh types (cubes, spheres, etc)
added setters in Mesh
Null check on error callback
added SGL.cpp the definition init function to avoid possible linker errors
renamed Geometry.h to Picking.h and removed Intersector.h, move Intersector class def to Picking.h
update readme
added default target and position. Removed translation function
added accessors for Camera vectors
associate mesh attributes with shader attributes automatically
added functions to create wireframe meshes from a vertex buffer
new uniform functions
Added constructor to vertex attribute. removed debug line from mesh generator
added getter for rotation
Merge branch 'develop'