The purpose of this program is to compare two versions of an
Internet Draft and as output produce a diff in one of several
formats:

	- side-by-side html diff
	- paged wdiff output in a text terminal
	- a text file with changebars in the left margin
	- a simple unified diff output

In all cases, internet-draft headers and footers are stripped before
generating the diff, to produce a cleaner diff.