Add BufSetOption hook support
Centralize file mimetype detection in mime.kak

This way, 'file --mime-type $buffer' is called only once per file
rather than once per filetype detection hook.
Update TODO, README
move cpp indentation to helper hidden commands
update TODO
Do not use eval for grepcmd, as it will evaluate \ escapes as well
tweak style cpp.kak
indent cleanup, correct erroneous 3 spaces indent
deindent now deindent non completely indented lines

If indent is 4 spaces, and a line has only 3 leading spaces, they
will get removed. a-< can be used to avoid this behaviour.
align always insert at selection begin
Use Q for macro recording and q for replay, document macros in README
Extract InputHandler from Client
move Client::m_name to context, no more need for DraftUI
extract InputHandler to input_handler.{cc,hh}
tweak initial debug infos
fix invalid value handling for yes no ask options
write assert failed info to debug buffer
remove idvaluemap, use unordered_map in place
move is_horizontal_blank to unicode.hh