Delete trailing whitespace in help/Docfiles

Additional functionality for abbreviations.

1. The labels library has been merged into
markerLib and the src/labels directory eliminated.
2. Have added markerSyntax structure.
3. Operations on abbrevs used to all be in
structure Q, even those that didn't deal
with quotations (like UNABBREV_ALL_TAC). Now
markerLib provides all abbrev. operations and
these take terms. Operations that benefit from
quotes, e.g., ABBREV_TAC, MATCH_ABBREV_TAC, etc.
are still to be found in Q.
4. Abbrevs are kept reduced by the simplifiers and
there is a REABBREV_TAC which can be separately called.
This sorts abbrevs topologically, so that they get
restored in a sensible order.
5. For situations where one wants to get rid of all
abbrevs, apply a tactic, and then restore the abbrevs,
there is WITHOUT_ABBREVS: tactic->tactic.
6. Have added a simple topological sort to Lib.
7. Updated proofs in the src directories, and also
in examples/lambda.

Huge number of check-ins, implementing change to .doc file syntax.
Now the rule for text within braces is that it appears as given, but
that braces must balance. If you want an unbalanced brace, you can use
\lbrace or \rbrace. No existing .doc file uses unbalanced braces.
Also, there is now no need to use \noindent. In fact, doing so
will get you a complaint from the parser. Similarly, use of \ or
{} characters outside of verbatim text blocks will cause griping.
All of the new files have been generated by a parse-then-print process
from the old files, and it's possible there are errors. If you ever
have a spare moment, casting your eye over a random selection of these
might help to find errors.

Finished documenting the Lib structure.

New versions of docfiles.