Smooth abstract and intro

- Switch from "contextual co-occurrence learning" to "distributional learning of word meaning"
- Add intuitive Alice-Bob example of distributional learning
Fix Berry-Rogghe, add Andrews, Vigliocco, & Vinson 2009 (not used yet)
Use term "distributional learning" more, minor fixes
Clearer methods section
Proper year for Salton & McGill
Apply Clark's rules a little
Footnote about excluding and catch trials, formatting
Smooth the matrix discussion, writing fixes
Add both years to Wittgenstein
Add 2013/11/24 binary