Tiny improvement, do not emit text/x-math-config script section if not needed
Merge pull request #22 from woudshoo/mathjax-improvements

Tiny improvement, do not emit text/x-math-config script section if not n...
Minor spacing tweak to navigation.
Add and export PREVIEW.
Tweaks to injections handling. NEWS updates.
Minor tweaks to PREVIEW.
Make WRITE-PAGE overwrite existing pages by default.
Release: 0.9.1!