Delete trailing whitespace.

Delete trailing whitespace.
Comment VT52, ANSI defines out of levee.h so they can be done on the command line.
Remove dead code.
Disambiguate levee code from standard library functions (as the original author has
done in later versions than we are using):
  refresh -> lvrefresh
  scan -> lvscan
  getcontext -> lvgetcontext
  getline -> lvgetline