Mass prune

[pottedmeat7]

Removed many features and code, Including:

• All digital/analog button remapping
• Keyboard input mapping
• Device Offset features
• Command line project
• Creation of Virtual Devices
• Device Input Redirection
• Hook interfaces used for above features
• Removed handled Messages to Server Driver for the above features from VRInputEmulator lib

I also updated ServerDriver and VirtualDeviceDriver to use the newer IVRDriverInput interface and all the necessary virtual function definitions.

There are still references to likely unneeded features for motion compensation. I also have not touched any of the UI layout so that likely will have undefined references. Many of the UI pages can be removed with only the motion compensation pages remaining.

This is just a checkpoint on the work. I probably can do more. However It would be nice to see once the UI compiles, if this pruned code still works to provide the previous motion compensation features required.

[pottedmeat7]

Just pushed the obvious deletions to the UI. This code compiles. I will need more info on the procedure to test and run it. However the current state, should let you choose different MC options and attempt to run MC in real-time. I don't know if the actual MC correction will work fully through openvr.

[rosskevin]

I'm going to accept and merge this PR as the starting point, @dschadu has continued work from this.