Fix issue #259 : Load optional GRFX flle XML nodes after connections have been made and display errors if any fail
These nodes are : 
"command" 
"schedule" 
"iamgraphstreams" 
"render" 




git-svn-id: http://graph-studio-next.googlecode.com/svn/trunk@432 c2f33eb2-41b2-391d-4cb4-d9d0608729ba