fixes #89

Very small change to code, lots of change to expected output of interpreter!
implement 0-based tuple indexing; fixes #82
update documentation for #82
implicit :prove all properties when no argument given

closes #93
Add basic support for :exhaust

Fixes #94. We should look into the :exhaust optimization later if necessary
tweaks to documentation and Salsa20 fix from Sean
Merge branch 'master' of https://github.com/GaloisInc/cryptol
Merge pull request #91 from TomMD/master

Use tf-random for higher-quality randoms.
Fix #101 by defining bitSizeMaybe

intSize was undefined, causing repl terminate.  This is probably because
the incorrect type signature using the scoped type variable (`:: a`
should probably have been `:: SBV a`) either way, bitSize and
bitSizeMaybe should use the same code when the size is finite.
REPL tab completion now works on all words, not just the first one

This addresses issue #99.
Use of CPP implies need for the CPP pragma...

Not sure how it built and gave me the positive result but not
having CPP pragma is clearly wrong.