Standalone PV finding on CPU and GPU

Features:

• Velo Kalman on GPU
• PV standalone on CPU
• PV standalone on GPU
• PV checker

to do:

• adapt simplified Velo Kalman to use new event model
• save Velo Kalman states in separate array
• re-integrate CPU PV finding into sequence properly (was removed to fix merge conflicts)
• re-integrate GPU PV finding into sequence properly (was removed to fix merge conflicts)
• use same function on CPU and GPU (device -> _host device)
• clean up code
• provide MC PV binary files
• fix segmentation fault