Two more External Core bugs

Two more bugs, both of which I was able to fix (patches attached):

- MkExternalCore.lhs didn't properly handle character literals greater than
0xff. It would generate code that contained something like (1010101::Char),
which made no sense. I changed it to use type Int instead of Char for these
literals.

- LexCore.hs ignored the sign of floating-point literals (so if a program 
contained -1.0, it would be parsed as 1.0). I fixed it.

-- 
Kirsten Chevalier * krc@xxxxxxxxxxxxxxxxxxx * Often in error, never in doubt

parserLexCore.patch
Description: Text document

coreSynMkExternalCore.patch
Description: Text document