Add %rec{...} string that recursively expand %block inside

the result is then used as one token
make.kak: use %rec rather than :exec hack in errjump
minor code style tweak
Support jumpclient in make.kak
update TODO
code formatting tweak
Fix crash caused by attempting to close a nonexistent DIR*
Merge remote-tracking branch 'jjthrash/fix-closedir-crash'
Code cleanup in list_files