very basic acceptance tests on free format

Will try to parse every file available at /private/samples/freeFormat.

(errr... not now; we don't even know how the parser or lexer will look
like)
test hello world sample
very basic grammar (actually empty) just for tests

Now we know how to compile (though we can't get past that yet).
working hello world compilation

The grammar itself has some ambiguities that makes ANTLR engage full
context matching (on userDefinedProcedureSection).