Improve DESCRIPTION
Minor reorg to make profiling easier
Simplify parsing
Combine parser documentation into one file
Simplify introduction parsing
Faster environment cloning
Eliminate unnecessary clone
Remove ... from object() since not needed
Remove out of date usage function
Pull out write_if_different.
(Implemented in roxygen3. Still rather slow)
Not very successful attempts at making profiling easier
Faster technique to find UseMethod calls
Whitespace tweaks & remove old comment