folder/Maildir: cache getfullname() value
folder/Maildir: cache getfullname() value

We use getfullname() very often (thousands to millions), yet we
dynamically calculate the very same value over and over. Optimize this
by caching the value once and be done with it.

Signed-off-by: Sebastian Spaeth <98dcb2717ddae152d5b359c6ea97e4fe34a29d4c@SSpaeth.de>
Signed-off-by: Nicolas Sebrecht <347709267ddd1958560c4c317ea3fd613f10a719@laposte.net>

frioux/offlineimap,frioux/offlineimap