Try to unify objective c and cpp in a c-family.kak file
use printf rather than echo in c-family.kak

According to POSIX, echo with a backspace in any arg is undefined
behaviour...
Handle SIGCHLD signals when piping
Pass a BufferRange to highlighters, fix subregions

Regions highlighter can now correctly be applied to only subrange
of the buffer, fixing some corner cases in recursive regions.
Use a select based event handling and fix deadlock
Revert "Handle SIGCHLD signals when piping"

This reverts commit 8208e75294b4eb016ae578f9ae132d9f8dfe4785.