make addRelativeToBase() and addRelativeToVia() return the link added, or null; copy getAnnotations() from CrawlURI
for ARI-3712, add extracted links relative to both via and base, and annotate with "extractorSWFRelToVia", "extractorSWFRelToBase", or "extractorSWFRelToBoth" if resulting link is the same whether relative to base or via
Merge pull request #70 from nlevitt/ari-3712

for ARI-3712, add extracted links relative to both via and base, and annotate with "extractorSWFRelToVia", "extractorSWFRelToBase", or "extractorSWFRelToBoth" if resulting link is the same whether relative to base or via