Moved menuCopy to CONTEXT_MENU copy constructor.

Resolved HOME hot key conflict between menu entry (Zoom Page) and event assigned to the hot key in the ACTION_MANAGER.
Conflicts:
	pcbnew/menubar_pcbframe.cpp

Key events are handled by wxEVT_CHAR instead of wxEVT_KEY_[UP|DOWN]. Fixed issue of chars that require modifiers (e.g. ? is Shift+/ on US keyboard layout).

Hot keys specific to a tool have priority over global hot keys (TOOL_ACTION scope: AS_GLOBAL/AS_CONTEXT is finally handled properly).

Renamed [class_]drawpanel_gal.[cpp|h] to [class_]draw_panel_gal.[cpp|h] to follow current naming scheme.

If tool was previously active and it is called again, it is brought to the top of the active tool stack.
It fixes issue of dragging of items that have EDIT_POINTs, when dragging was activated by hovering over an item and using hot key.

Refactored code that handled zooming events.
Added PCB_RENDER_SETTINGS::Get/SetSketchMode().
PCBNEW_CONTROL reacts to hot keys changing display modes (sketch via/tracks, high contrast).

ROUTER_TOOL events have temporarily changed their hotkeys assignment.

Selection clearing is invoked using TOOL_ACTION object rather than its name.

Most of the GAL tools are activated by corresponding buttons on the right toolbar.
Removed menu entry for PNS router (as it is activated as the usual "Add track" tool).

Removed an unnecessary header from class_board_item.h.

Added REASON enum for Reset() function, so tools will know why a reset occured.
Fixed SELECTION_TOOL (it was bailing out, when a new board was loaded and some items were still selected).
Added removal of VIEW_ITEM groups after changing layers and removing items.