v2.0.0-rc2

good re-write of D&D with generic non jquery code. this fixes the following:

• #1329 D&D wasn't working correctly in 2.0.0-rc
  went through entire code with fine comb. "had to change 'drop' signature to have 2 elements (original drag and helper) do handle both cases
• #1102 we no longer make a copy when dragging between grids (just re-parent)
  so all actions and settings stay the same.
  Only time we make a copy is if dragging from an external toolbar and user has helper to clone item
• #1335 some fixes for new load() API