Remove trailing whitespace in src/

Pushing things so I can work on case constant flipping.

Added Tactical.PRED_ASSUM. It's similar to PAT_ASSUM but uses a predicate to
pick the assumption.

Added blastLib.FULL_BBLAST_TAC, which attempts to use "blastable" assumptions.

Make blastLib.BBLAST_PROVE smarter with respect to counterexamples (existential
goals). For example,

> blastLib.BBLAST_PROVE ``?x y. x + y = 12w : word8``;
val it = |- ?x y. x + y = 12w: thm

is now possible, and we also have:

> blastLib.BBLAST_PROVE ``x < y = x <=+ y : word8``;
Found counterexample:

y -> 255w

and

x -> 0w

Exception- SAT_cex |- (0w < 255w <=> 0w <=+ 255w) <=> F raised

The printing of counterexamples is controlled by the trace
"print blast counterexamples".

Add fcpSyntax and tidy up related code.