[+] vector_2 typedef
close #2

Thanks to BlackHawk74
template fixes in /include/cg/io
Merge pull request #5 from ZumZoom/io_fix

template fixes in /include/cg/io
Contour class refactored
fat commit

[+] some operations. I'll push some interfaces, pull implementation for
them
[+] triangle_contains_point example
[+] bug fixes
Merge branch 'contour_fix'
Merged with main branch
Some fixes in merged branch