ReadLegacyAddons modifies its vectors of maDecks and maPanels in this case, but
a load of things have (c++) references contents of the original contents.

Its such a rats nest that the easiest thing seems to be to make them
vectors of shared_ptrs and hold DeckDescriptor and PanelDescriptor
by shared_ptr and it all works out

Change-Id: I3f628e12c7d5f4224d14d5e0769e450ce893fb54