Reasons:

1. No-one seems to remember why we are building with /MT
2. The thread local vars causing race conditions [1] which is a blocking issue for supporting USD on windows.
3. We have to ship the CRT libraries anyhow for python.
4. Intels TBB allocator doesn't like /MT

This patch moves blender over to /MD and moves building of the deps to VS2017 including an new lib folder (win64_vc15) so it should cause minimal disturbance.

Passes the unit tests in both release and debug builds with the same pass-rate as the MT build (one failing test in debug on both builds)

noteworthy changes:

• yaml-cpp needed a version bump to 0.6.3 build with vs2017
• OpenCollada needed a similar fix (pull #610) but that hasn't merged in nearly a year so i added it to our patch
• Both openVDB and OpenColorIO needed a preprocessor define otherwise they defaulted to a dllimport interface which was a warning for the /MT build but a straight up build error with /MD

[1] https://developer.blender.org/D5387