and while there document some missing keys.

* hide-pre-context: if nonzero hide the start and end line of a pre block (i.e. ```). Defaults to zero. * add: hide-pre-blocks: if nonzero hide by default the body of a pre block; push-button can be used to toggle visibility per-block. Defaults to zero.

free ui.c from (strictly) non-ui code

After a talk with tgl (thanks!) about defaults, I'm convinced this is a sensible default. For people who don't like colours (myself included), telescope will honour the `NO_COLOR' env variable. Then there is also the set enable-colors = 0 for the config file. We could go further and provide a flag like -O var=value to set some values without the need for a config file eventually.