This simplifies the (already simple) SELECTION_AREA class. It is also
moved into KIGFX::PREVIEW and put in the common library, where it can be
reused by other GAL-aware tools (not just in Pcbnew) in future.
New virtual class ACTIONS is added as a member to EDA_DRAW_FRAME so
that the TOOL_DISPATCHER can have access to the appropriate derived
version of TranslateLegacyId()
John Beard
Jon Evans
Tomasz Włostowski
Chris Pavlina