tweak/mobile_markitup_menus

Clicking a button with a dropdown on a mobile page makes it a dropdown. The few buttons that have default actions not on the menu (e.g. colour picker) add that default item to the menu.

Not this doesn't work on pages with markitup editors which aren't on a mobile enabled page (e.g. the D&D notes section).

I like this

I'm like 80% of the time on my phone, so a big yes, please.

I'm 40% on mobile with some days more or less. But yes, yes, please!