Mobile support

[cben]

This is mostly a CodeMirror problem.

Viewing pages works on Android and iOS (don't know about Firefox OS and Windows Mobile but should work).
Clicking inside tends to zoom in a lot (at least on android), making it not very usable. There are stackoverflow answers claiming setting initial font big enough prevents this (perhaps it's even enough to enlarge font of the invisible textarea?).
Editing is even harder, because of CodeMirror might not reliably get presses from soft keyboard, because of the inconvenient zoom, and because of lack of various keys: arrows (should implement click to edit math cben/CodeMirror-MathJax#9), codemirror shortcuts and annoying to type markdown punctuation (toolbar #64 would help).

[cben]

CM 5.0 landed the mobile branch.
Positive opinions here: https://plus.google.com/115360165819500279592/posts/iimARADDM7W

I probably should to move to 5.0 and lose for now my (hackish) RTL support;
if I care about RTL (hint: I do because I live in Israel) I should already leave my feedback on the CM direction branch to increase chances of it ever landing...

[cben]

Google's new "mobile-friendly" signal says (unsurprisingly) that Mathdown is not mobile-friendly.
I doubt their algorithm knows the CodeMirror I'm on is not friendly, but it gives other useful advice at:

https://developers.google.com/speed/pagespeed/insights/?utm_source=MFT&utm_campaign=MFT&utm_medium=incoming-link&priorityGroup=USABILITY&url=https%3A%2F%2Fmathdown.net%2F

[cben]

There are known/suspected issues with Firepad / CM 5.x combo.

[anpc]

Should test how it'll look, see also #37