Remove duplicate files

[ryandesign]

There are several duplicate or nearly-duplicate files in the repository:

• bitap.c and bitap.c.orig
• checkfil.c and checkfile.c
• checkfil.h and checkfile.h
• dummyfil.c and dummyfilters.c
• io.c and io.c.orig
• preproce.c and preprocess.c
• recursiv.c and recursive.c
• utilitie.c and utilities.c

What's going on? Can the differences between the two files in each set be resolved and the duplicate files be removed?

[Wikinaut]

Probably I wanted (then) to keep the old and original files - as they were difficult to find.

Perhaps I need to separate everything "old" into an "archive" branch (there are already branches for older/different stuff which I found over the decades).