Allow blank lines in the description

[cbandy]

Fixes #10.

This one took a while to track down. By making UntilLineEnd optional, everything up to ( NL / !. ) was optional. At EOF, LineEnd was repeatedly matching !. without advancing the pointer.

Unfortunately, lookahead assertions are bugged with the -switch option, so I had to drop it to make this work.

[cbandy]

After some more sleep, I have one more idea I'd like try.

[cbandy]

All set. Only one EOF is needed in the grammar, at the very end.

[muhqu]

I don't like the appending of the \n much, but I also don't have the time atm to figure out an alternative.

I'm currently only viewing the PR on my phone, will merge and version bump etc as soon as I get back on my macbook.

Oh and thanks for the contribution! :-)

[cbandy]

IIUC, the GherkinParser is the only exported interface to the PEG grammar/parser. It seems reasonable to me that we ... set/ensure some invariants on the buffer that we pass to the parser.

In this case, ensuring every line has an end character makes the PEG grammar/parser simpler and safer.

[muhqu]

@cbandy I don't think a parser should alter the input it gets passed in, eventhough the passed variable is immutable. Anyway, I'm more happier to fix the issue than fighting for my opinion on this. ;-)

Thanks for the contribution.