Fix for 1726595: notes composed only of whitespace caused a crash.

git-svn-id: https://crawl-ref.svn.sourceforge.net/svnroot/crawl-ref/trunk@1492 c06c8d41-db1a-0410-9941-cceddc491573

Created by  haranp  on May 29, 2007
XEUQ36QJIYDPC46OS3HYV6ORCN426PJDZJZVDPAO22OHTRUWDV6QC
Change contents