Merge pull request #346 from alexrudnick/master

Fix for decision trees with binary=True
applied patch from Tomonori Nagano to fix pos tag issue, resolves issue 347
fix indentation error; still an issue with line 323
re-apply patch from Nagano
Escape reserved chars in Tree.pprint_latex_qtree()
Merge pull request #348 from stesh/master

Escape reserved LaTeX characters in nltk.tree.Tree.pprint_latex_qtree()