Some grid/zoom tools are left in PCBNEW_CONTROL because they currently
depend on Pcbnew-specific class members. Once refactoring is done to
make it possible to use all zoom and grid controls outside of pcbnew,
these last tools can be moved to common to match their ACTIONs.
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()
Add a class TOOL_MENU, which provides a management class for a
CONDITIONAL_MENU and a set of CONTEXT_MENUs. The aim of this is to
provide a central place where all TOOL_INTERACTIVEs can get a "basic"
context menu that either they or other tools can register new items and
sub-menus against.
This means that "top-level" tools no longer need to manage the lifetimes
of any CONTEXT_MENUs that they add, and can also delegate simple menu
display functions.