Ocassionally, one would want to translate the same string used in
different contexts in diffrent ways. This patch provides a wrapper
for msgcat::mc that trims "@@" and anything coming after it, whether
or not the string actually got translated.
Proposed-by: Harri Ilari Tapio Liusvaara <hliusvaa@cc.hut.fi> Signed-off-by: Shawn O. Pearce <spearce@spearce.org>