Use StringViews for some helper functions in selectors.cc
Support single char StringView

remove single char escape function overload, add unescape function
Use unescape rather than a regex in command manager parsing
minor code cleanup
Change Value to be non copyable
Tweak flags implementation
update kakrc highlight, add alias/unalias
update cpp highlight, add constexpr
Reuse existing buffer when creating a fifo one

That way, client having this buffer already visible wont switch to
another one due to previous buffer getting deleted
Fix bug in insert completer deregistering

The context options might change, as the context might have a different
window/buffer from the one at creation. So we need to store the correct
option manager rather than ask the context for it.
cpp.kak: tweak cpp-alternative-file implementation
Fix potential alignment bug
Simplify RemoteClient creation code
Fix escaping of ' in single quote python strings
Add initial jedi python completion script
Remove clang cleanup hooks once they ran