Fixed issues with Wipe Effect where it is changed from default duration

Number of pulses was allowed to be set to 0 which would cause a divide
by 0 exception.
Create a abstract method that is called when Targetnodes change.Effects can use this to do some sanity checking or setup work like validate colors for the nodes underneath it. This lets all the color property work happen right when it has new nodes instead of waiting until rendered. Eliminates having the need for null or black colors to determine a new effect. Frees the color/colorgradient getter from processing a bunch of logic that slows things down.Fixed up all effects to implement this method. Those that need to do nothing just have empty implementations.
Fix unneeded dispose causing the editor to crash on closing.
Fire off rendering of single elements ahead of the queue so people can work on them while other rendering catches up.
Resolve merge conflict.
Add TargetNode override.
Merge remote-tracking branch 'remotes/giz/master' into ProposedMerge
On my system using Giz's V3 dir from drop box, I started V3, clicked on Configure Previews and added a preview.  Got an NPE at GDIControl.cs line 131.  Graphics was null.  Apparently this happened because AllocateGraphicsBuffer failed to set up backbuffer because Height was 0.  I traced this to the Data that GDIPreviewForm.cs was using in its Setup routine.  This change just stuffs some non-0 values in Data in case it come in bad.  Dunno why Data was bad, but suppose it has something to do with the gdi/d2d switch?
Merge branch 'master' into ProposedMerge
Merge remote-tracking branch 'remotes/komby/master'
Fix a few things in the solution file after merges
Merge pull request #44 from sall/master

Merge from sall/vixen