Fix option handling
Fix Wayland event flushing

Before this patch, the flush loop could get stuck
Even more cleanup and commenting things
Minor code cleanup
Do not update unrelated layer surface settings on configure event

Before this patch, wlclock would always update all layer surface settings on
every configure event. This is known to create a feedback loop with faulty
compositors (see https://github.com/swaywm/sway/pull/6709). While wlclock did
nothing wrong before, not updating these settings is more idiomatic.
Only include execinfo.h when glibc is used
Use correct OS macro for guarding execinfo.h
Fix multi-cussor mishap
Improve signal handling

This patch replaces the signalfd based signal handling with a more traditional
approach. Since this is not only more reliable, but also more portable, the
compile time option to turn off signal handling has been removed. It was only
optional before based on signalf being a linux-ism.
Use global context
Deprecate non-sourcehut forges
Fix handle-signals build option
Remove unused surface functions
Bump versiont to v1.0.0
Change face/hand line width configuration

Also decided there will be no additional hand styles, so removed
--hand-style option. Xclock like hands can be enabled by setting the
hand width to 0 (default).
Rip out frame callback

Apparently, requesting a callback is asking "when can I render the
/next/ frame?", not asking "when can I render /this/ frame?". Huh...
Update wording in README and man page
Render on callback