Remove unnecessary structure bracketting

As per 89fc99bc3, but on as many examples as a grep -R can find.

Remove some duplicates of the theorem TRUTH.

These are:
• INFINITE_DEF and IN_LIST_TO_SET (replaced with overloadings)
• IN_APP_applied and IN_ABS_applied (inadvertently generated)

Also, made changes to try to avoid new definitions in listTheory accidentally having a "_DEF" suffix instead of "_def". Old naming inconsistencies still remain in listTheory (e.g. EXISTS_DEF, FIND_def and FLAT).

These changes will break a few proofs but patches should be trivial (i.e. removing references to these TRUTH theorems and/ or renaming "_DEF" to "_def").

Remove calls to print_theory in enumfset/script files.

print_theory is fine to call interactively, but just adds verbiage
when done as part of a build. Having done a build, looking at a
Theory.sig file is a good way to see what one has achieved.

trailing newlines in *.{sml,sig} files from src/ removed

Trailing newlines from SML files in src/ were rendered in HTML documentation.

Latest updates to enumfset code (from Lockwood Morris).

Builds on master.

New 'enumerated finite set library' by Lockwood Morris. (As delivered.)