Simplify Trampoline datatype with optimizations.

Conflicts:
	libraries/Native/Trampoline.js
	libraries/Trampoline.elm
Update trampoline docs to new interface.
Fix ctor reference
Update test case
Add Trampoline module to docs
Remove extraneous newline
Remove KeyCode type from docs in the Keyboard module

It has moved to Keyboard.Keys
Add emptyMultiLineFieldState to docs