Added disabling option for lim tutorial
Merge branch 'master' of https://github.com/libigl/libigl

Conflicts:
	tutorial/607_LIM/main.cpp
started LIM section in the tutorial
Merge branch 'master' of https://github.com/libigl/libigl
Merge commit '2bae5b6002557235224942acb717a312d5ee1d22'
Merge branch 'master' of https://github.com/libigl/libigl
Fixed some windows specific issues
added notes on polyvector fields
Merge commit '2341af78cad7d594d7c3b1ebe91d8fb52ec19773'

Conflicts:
	tutorial/607_LIM/main.cpp

- viewer timer is now cross platform
- glew is now properyl included in all the viewer files
minor fix in the cmakefile for planarization, removed comiso dependency