Declare the permitted alphabet tables and code2value tables const.
Declare the type descriptor and input buffer args of some functions as const.
Declare most internal, constant tables as const, particularly the
"specifics" structures and the tables they point to.
Declare the tags[] tables in skeletons as const.
Constify the PER support structure.
Constify a few other private tables in the skeleton code.
Avoid an unnecessary table lookup and its accompanying table (final_chunk_type[]).
It's actually more efficient *not* to create a mutable static variable to hold this constant string's address.
Merge pull request #46 from wiml/constify

Move as much data as possible into non-writable text by declaring it const