GIL should have a sane syntax

[giltho]

The current syntax of GIL is a bit insane:

• lists are captured by {{ }}
• l-nth should should probably be replaced by an appropriate indexing operator
• integers are postfixed with i, instead we should go with the ocaml-like notation of n+ is an integer n+\.n* is a float.
• ...

We should:

1. Choose a new, better syntax
2. Have a script available that translates the old syntax into the new syntax
3. Translate every GIL file into the new version syntax
4. Get rid of the old syntax entirely, but keep a module available a parser and rewriter old-syntax -> new-syntax just in case.