* Closed a loophole in HolSatLib failsafe mechanism.
* Replaced MiniSat's DIMACS parser with my own to avoid
build dependency on zlib, which HolSatLib does
not use. Thanks to Anthony for motivation. Updated
docs.

Summary: tautLib upgraded to use HolSatLib engine.

Details:
* tautLib signature (and behaviour hopefully!) is unchanged.
Internally, TAUT_CHECK_CONV now uses HolSatLib.
* HolSatLib can now handle Boolean-valued conditionals. This
was forced because tautLib handled them.
* We now have full drop-in support for zChaff, via a proof translator.
* HolSatLib now deletes temporary files.
* Legacy HolSatLib interface dropped in favour of simpler
interface with single entry-point, plus some convenience
wrappers.
* examples/miller/m renamed to selftest.exe; now works with build -selftest
* build-sequence changes: src/compute and src/HolSat/* moved above src/taut;
examples/miller stuff condensed into one entry
* build.sml patched to handle zChaff proof translator (in C++).
* New windows binaries for MiniSat and zChaff proof translator.
* Changes/additions to HolSatLib interface rippled to affected files.
* Documentation updated. In particular, HolSatLib section in Description
had to be almost completely rewritten.
* HOL builds to selftest level 1 on standard kernel, and level 2 on
experimental kernel. Level 2 failures on standard are non-critical
and authors have been informed.