Declare most functions before using them. I declare some functions in
ack.h and some in trans.h (because trans.h declares type trf). I
leave declarations of scanb() and scanvars() in .c files because they
need type growstring. (I can't #include "grows.h" in another header
file as long as grows.h doesn't guard against multiple inclusion.)
Functions used within one file become static. I remove a few tiny
functions. I move a few functions or declarations to more convenient
places. Some functions now return void instead of a garbage int.
I feel that keyword "register" is obsolete, so I removed it from where
I was editing. This commit doesn't touch mktables.c
