unify the tools

[pkra]

A unified tool would seem to make more sense.

[pkra]

This should cover most of it already.

[knoxell]

Hey @pkra,
is this still wanted and would be merged?

I'm interested in having all these tools in one.
I imagine something like mathjax [command] [options] 'math' > file.svg with

Commands:
  am2htmlcss
  am2mml
  am2svg
  mml2html
  mml2htmlcss
  mml2mml
  mml2svg
  mml2svg-html5
  tex2html
  tex2htmlcss
  tex2mml
  tex2svg 

Looking at yargs/yargs#225, this could be implemented with copying most of the existing code.