v1.1.1

This release mainly fixes the write_obj(...) and write_textured_obj(...) functions to now also write out the texture triangle indices (tti), when they're present in a mesh. Previously for meshes who used a different set of texture triangle indices, this could cause weird artefacts on the top of the head because the tti were not written to the obj. [c253197]

Other small changes/improvements:

• Moved write_obj(...) and write_textured_obj(...) into a separate header, eos/core/write_obj.hpp, so that including Mesh.hpp doesn't result in transitively including <fstream> and <string> [a040c0e]
• Prefixed all header guards with EOS_ in the eos::core namespace to reduce possible name collisions [4381fd1]
• write_obj(...) now also inverts the y axis of the uv coords, to be consistent with write_textured_obj(...) [7ce2918]
• setup.py now checks for CMake 3.10.0 on Windows [3dd69f7]