Update .gitignore, split projects and dependencies

Split projects and depencies in solution, and add more to .gitignore
Add DoubleAction as reference material
Some misc fixes and additions
Fix eol settings
Start to rewrite splines as simpler classes.
The old stuff is a mess of structs and classes, this should be a mix of classes for splines and structs for vectors using Valve's mathlib (see Reference/DoubleAction-master/src/(public/)mathlib/ directories) - need to find a way to integrate it with opentk vectors somehow too