v0.7.8

Diff from v0.7.4

• Bugfix: HTML-encode in Math-inline
• Update Mathjax
  • Use mathjax@3/es5/tex-svg-full.js instead of mathjax@3/es5/tex-mml-chtml.js
• Update webfetch
  • can read much ways of <meta>
• add --js option
  • can insert js files
• remove polyfill.js from default template

v0.7.4

This is not yet 1.0.0.