Fix WikiLink deserialization bug.

The WikiLink field is stored as three separate fields in Solr, but as one column in the tab-delimited representation. The different representations were not properly handled by the deserialization code. 

This also adds code to sanity-check character offsets from the TAC2010 corpus, and fixed a small parallelism bug due to the introduction of a transient dependency on clearnlp (from taggers.)