escapes: pretty-print some escapse and avoid ESC in debug logs
escapes: pretty-print some escapse and avoid ESC in debug logs

ERR("Hello '%c'", ESC) would result in "Hello '\033'" which means
the parent terminal (another terminology, maybe) would then try to
interpret ' as an escape char (ESC is \033 or 0x1b), and so it would
then forward more escapes to the parent.

Also, avoid printing BEL (and, well, beeping) when we are just
printing an error log.

I believe all those "Unhandled escape" logs should go to WRN or higher
log levels. Any thoughts, @billiob ?

See T2506 (for the test file)

godfath3r/terminology,godfath3r/terminology,ihorlaitan/terminology,ihorlaitan/terminology,ihorlaitan/terminology,godfath3r/terminology