Fix src/rational for tight equality

Remove some code from schneiderUtils along the way that can't have
ever worked (and wasn't being called). Some of it included parsing
calls to ancient if-then-else syntax (gd => t | e).

Reconcile store_thms with diverging names in db and val binding

Don't export ERR from HolKernel

Remove TABs from src

Will also make selftest to check that they aren't introduced

Remove eqtype declaration for term type

theorems FRAC_MINV_1 and RAT_MINV_1

Delete trailing whitespace

some shorter proofs for fracTheory

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

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

Get this directory to build again by hacking into the offending proof in
what is probably quite a blundering way. Also some reformatting - I'm
not keen on tabs, nor lines longer than 80 characters.

Initial version of theory and libraries of rational numbers added.