With lots of elements the wipe timeslice can round down to 0 ms and the loop never finishes.
This sets it to a minimum of 50 ms.
Fixes Greg Skull's 'hang' with his sequence.
Greg S. had a sequence that had effect that had no nodes to apply to.  This can lead to exceptions later on other code seems to count on the fact that effects always have some nodes under them.  This change weeds them out on reading.
Nutcracker like to have a rectangular set of elements to work on - a collection of groups that have elements. If the user applies Nutcracker to an irregular shape of groups/elements bad things happen.  Greg S. has a sequence like this.  A Nutcracker would not render in the Grid and would crash if the Effect editor was invoked.

The root cause was weakness in the StringCount and PixelPerString calculators - and the fact that there are two (different) copies of this code (one in NutcrackerEffectEditor/NutcrackerTypeEditorControl.cs and one in Nutcracker.cs).  This change fixes the same defect in both of them and brings them into alignment to behave the same.
Merge remote-tracking branch 'remotes/billlutton/weedoutEffectsWithoutElements'
Merge remote-tracking branch 'remotes/billlutton/fixNutcrackerNonRectangular'
Merge remote-tracking branch 'remotes/billlutton/foxWipeRenderLoop'
Squashed commit: James' work for delayed playback start and playback looping.

commit 41453d7646a38c6cfc29b250b7bbbaefa63fbd73
Author: James Bolding <bolwire@cableone.net>
Date:   Sun Nov 17 16:18:45 2013 -0600

    Added message to status bar to indicate when delay play is in use, also does countdown.
    When play is clicked and delay play is used, the icon will change to an hourglass.

    Adding looping ability, works with selected portions of sequence as well.
    Added icon for toggling looping on/off

    Looping and delayed play options disable each other, you can use one, not both.

    There is a 500ms pause between loops to allow other things to finish processing.

    MenuBar and ToolBar _Click items are now moved into the proper regions

    Updated ToolTips for Play Pause Stop and Loop to include the shortcut keys

commit 74ea335086bb19c02f06c9b5b163ec81d2abd5f3
Author: James Bolding <bolwire@cableone.net>
Date:   Wed Nov 13 17:39:10 2013 -0600

    Added red play button

commit 5ff61393ac6e05596063a603913b9c2e514f82c8
Author: James Bolding <bolwire@cableone.net>
Date:   Wed Nov 13 15:43:29 2013 -0600

    Updated the way the delay for playsequence() is handled and put code into proper regions
Minor changes to icons for the repeating stuff, and added more arrow icons.