bsdtextproc week #6

[Ben Fiedler]

These final diff features to support (group/line formats, dynamic function
matching) are proving the most difficult to add.
There's a lot of overhead necessary for each of them, as well as efficiently
tying them into the existing structure, which I am steadily building.
Implementing a custom printf-parser which is needed for the format lines
would be far more trouble than it's worth, but I think I have a solution
involving regex's and sprintf.

I have also begun to work (admittedly, only a small amount) on Ulrich's
mandoc branch in preparation for switching to that milestone.

-Ben