Generalize this option type, which is a timestamped list of
<line number>|<arbitrary string>. That way this type is not strongly
coupled with the flag-lines highlighter, and can be reused for other
use cases.
No defaults have been altered, just added the ability to do user override. The existing facespec had a background of 'black', which ends up looking a little harsh for people who do black text on a white background.
Level out the builtin commands loaded at startup in terms of format and
expressiveness. The following convention was followed:
* commands that take more than one argument have to be described along
with their parameters prior to the actual documentation, otherwise the
docstring consists in a capitalized sentence
e.g. `command <arg1>: do something`
* optional arguments are enclosed in square brackets, to comply with the
format used for hardcoded commands
e.g. `cd [<directory>]`
* describe the effects of the command in the documentation string and
omit implementation details unless they are relevant. Usually command
names include the name of the tool they use, so they don't need to be
redundantly mentioned
e.g. `tmux-new-pane <arguments>: open a new pane`
* document the format the parameters to the commands, or list them if
they are to be chosen among a list of static values (c.f. `spell.kak`)
