v0.3 - Many bug fixes and important performance improvements

This release marks a point when somewhat usable results, with reasonable processing time (< 20 s) have been achieved with datasets of sizes around 0.5M triples.

See the commit history for more details, but some highlights:

• Don't add duplicate facts or categories
• Shorten titles to MediaWiki's max
• Fixed silly code that allocated insane amounts of memory
• Better RDF parsing error checking
• Collapse multiple argument to same variable to comma-separated list

The usage is also slightly updated, with a dedicated flag for the out-file:

./rdf2smw --in mydataset.nt --out mydataset.xml