Log Message:
Update to inputproto-2.0.

"The first stable release of the X Input Extension Version 2.0 protocol
specification and header files."

XI2 provides a number of enhancements over version 1.5, including:
- use of XGE and GenericEvents. GenericEvents are of flexible length with a
  minimum length of 32 bytes.
- explicit device hierarchy of master and slave devices. See Section 4.
- use of multiple independent master devices (Multi-Poiner X or MPX).
- the ability for devices to change capabilities at runtime.
- raw device events