This means that non-top-level tools, for example EDIT_TOOL and
PCB_EDITOR_CONTROL can submit their own menus to the top-level tool's
TOOL_MENU, which will then retain a reference to it and make it
available for the CONTEXT_MENU that is shown.
- Finalize transition to BOARD_COMMIT (removed all remaining uses of PICKED_ITEMS_LIST) and implicit view/ratsnest updates
- Simplified SELECTION class, it now can be directly added to a VIEW
- Removed unnecesary casts and templates
- Introduced C++11 features (range based for, lambdas) where they improve code readability
- Added non-undoable COMMITs, which can be used to propagate change notifications to interested listeners (e.g. ratsnest/view)