Add a "make style" build target to run textlint

TextLint [1] is a tool to check your scientific writing for common style
errors. This patch adds a "make style" target to the LaTeX common
Makefile, which runs textlint on a Document's .tex sources.

[1] http://textlint.lukas-renggli.ch/
summary: Style fixes recommended by textlint
log: Add notes for Wednesday