osgwnormalmap now uses aphere as default model.

git-svn-id: http://osgworks.googlecode.com/svn/trunk@556 c67418bc-a6eb-11de-8ba5-91705c1537ed
osgwnormalmap documentation update.

git-svn-id: http://osgworks.googlecode.com/svn/trunk@557 c67418bc-a6eb-11de-8ba5-91705c1537ed