Fixes#288, but more-or-less as a side-effect.
The “mi” key in LS_COLORS was meant to be used for a missing link path, but it wasn’t really used like that. There was also a bug where control characters in a broken symlink’s path were assumed to be underlined, because that’s what happened in the default colour scheme, but this assumption doesn’t hold when colours were disabled.
The solution to these was not to introduce another configurable colour code, but to start using _overlays_ to alter a bunch of colours at once. The “mi” code will have to be added back later.
This commit changes the definition of Arg so that it knows about which values it can accept, and can display them in the help text. They were already being shown in the help text, but they were passed in separately, so one argument could show two different sets of options if it wanted. Now, the argument itself knows whether there are suggestions, so it doesn’t have to be passed in separately.
This means we can use it for other things, including listing choices when an option is missed out, without having to repeat the list.
With Misfire::BadArgument now only having two fields, it’s not worth using a constructor function anymore.
This commit adds to the parsing of the LS_COLORS and EXA_COLORS variables so that non-two-letter codes (keys other than things like ‘di’ or ‘ln’ or ‘ex’) will be treated as file name globs, and get used to colour files accordingly.
Fixes#116 for good.
