Samples should be de-VRPNified where convenient/possible

[rpavlik]

Since we aren't distributing a linkable VRPN library, the example apps should not depend on VRPN when possible since people go looking for a vendored-vrpn.lib and can't find it. In most cases, it's being used out of convenience for timing stuff (can use std::chrono), handing shutdown (can use a header poorly placed under osvr/Server). In a few cases, it's being used for math (like quatlib) - not sure the best thing to do there besides distribute Eigen.

I did a few of these changes earlier hoping that they would be an example of how to port the rest, I thought, but maybe not. Anyway, on request I ported another - SolidColor.cpp (also used unique_ptr to not leak render managers while I was at it) https://gist.github.com/rpavlik/141786b7b4656782e8c618975f8955a2

[russell-taylor]

Some of these ended up being instrumented for testing, so should really be moved to a test directory. They are built with all of the libraries that are available when RenderManager is. I think we probably want to make an example directory that has a CMakeLists file that enables it to be built outside of RenderManager, which will avoid the use of external libraries as much as possible, which does not need the rendering timing and such,