Profiling showed that the call to isUserDefined() took most of the time,
so we now fetch this only once for each style and remember the result and
use it in the inner loop.
The attached sample-file took aprox. 1m30s on a decent machine, now it is down
to around 2s.
git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1884917 13f79535-47bb-0310-9956-ffa450edef68
Dominik Stadler