String truncation here is a valid error that gets reported to the user.

A mutable type should always satisfy a const argument, yet gcc argues
otherwise.

Unoptimal (eg. will recolor over and over, O(n²)), but working!

I'm leaving them as "required" to fail by default.

Their values are applied at action/etc creation time rather than during match.
Required for fast matching, but even with old code, it's a large speed-up.

Easy to do by hand, but hey...

A temporary value did overflow 64 bits.

These currently can't happen, but let's fix that while I remember the
problem rather than have a nasty surprise in the future.