Strings properties and hash tables

[Andrea Corallo]

Hi all,

before I try reinventing the wheel, is there a suggested and or
precooked way we already have for having in hash tables string
properties considered when the string is used as key?

Ideally I'd just want to use `equal-including-properties' as test, but
this is not one of the three stardard accepted tests of
`make-hash-table', OTOH I can't trivially define a new hash table test
because we have no `sxhash-equal-including-properties'.

TIA

  Andrea