let the backslash escape only quotes (and itself), after all - $$list()
(one of the main users of this function) is commonly used with (windows)
path lists, so letting it escape anything would make a royal mess.

Change-Id: I2dae2e4508903e62c190c1497da68d53978118e7
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>