Update Qt5-based Matrix clients

• libqmatrixclient is undergoing a name-change, to libQuotient. Anticipate that a little.
• libqmatrixclient installed a ${LOCALBASE}/include/util.h which is awfully generic; move the includes into include/Quotient (again, in advance of the completion of the renaming). Reported by Jan Henrik Sylvester.
• quaternion just has a minor release with several-times-rerolled AppImage support (which isn't relevant for us).
• spectral has had several more tags done, but no official releases. The tags are build-numbers, really, so PORTVERSION=603 means build 603, and can be interpreted as 0.0.0.603 until there's a real release. This does mean that we'll hit a PORTEPOCH once such a release happens, when PORTVERSION drops back down to 0.0.1 (or whatever).
• spectral doesn't update to the latest tag (648) because that requires an unreleased libQuotient version (not an issue if you build from source with git submodules, but problematic in packaging).