README.utf fixes
Added some more functions to the IntInf interface.

These are mainly to support the application of the IntInf module to a
'hugeword' unit, which we can use to implement primitives for 1024 bit
words and more ... This needs documentation, but the names of the new
functions are similar to the GNU GMP names, and the GMP info pages are
rather good. There are examples of the use of the functions in
testintinfx.sml
.gitignore fiddles
trivial testrewite.sml change
Some units intended as a test of the lightning interface.

The interface is not quite right, but the lightning functionality
seems to be a step in the right direction, and this shows that the
binding is fairly stable, on an i386 platform at any rate.