Improve usability of openVV

This is very cool software, but you should make it easier for potential adopters to get started.  I picked this up to use on a project and forked at commit 66d79c65c114ec9a0df0d00a2b0e255bd1a032d8

I ran into some issues, particularly the absence of a readme or clear example of how to use.  I also found that it wouldn't compile, so I added a readme and fixed the compilation errors/warnings and it worked great.  

Let's share this with others.