support for utf-8 / unicode characters

[MrBenGriffin]

[MrBenGriffin]

EAdd. Exp ::= Exp "⌽" Exp1 ;
-- syntax error at line 1, column 22 due to lexer error
The inability to lex simple unicode character declarations is a shortfall.
It may be there's some way of addressing this, but the documentation doesn't mention anything.

[andreasabel]

By simply allowing unicode in the generated Haskell lexer, I managed to enable this feature for LBNF and some backends, including Haskell and Java.
For some backends, the testsuite reports errors: C, C++, Ocaml.

[MrBenGriffin]

Thanks for this Andreas. I will try again ;-D