Add -c option to split-sentences.perl

[jelmervdl]

Some documents contain extremely long lines of generated text (most often links to search page results) that take forever to parse with the regular expressions in split-sentences.perl. Using the -c option these lines can be completely ignored.

[kpu]

Ideally we'd replace buffering then splitting with splitting on the fly. Then if there's something long and no split we throw it out. Here I'm a bit concerned we're throwing out stuff that would correctly split. I understand your immediate need though.