Changes introduced by the module editor are updated in GAL canvas.

DXF export: fix incorrect export of polygons having thick outline (like zones): Thick segments of outline were drawn like lines with no thickness.
Fix ( workaround only) crash (Windows only) when a quasi modal frame (like footprint viewer) was called from a dialog (like the component properties dialog in schematic editor).
Very minor other fixes.

Cursor position is saved as a field in order to avoid drifting of items while they are being dragged and rotated/flipped.

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

Added preference for selecting tracks/vias/graphics if there is a module present in the selection point.

- SEGVIA becomes VIA
- Drill size moved from TRACK to VIA
- Removed shape from TRACK, becomes ViaType in VIA
- GetTrace becomes GetTrack, for uniformity
- Some minor constification and typo fixes

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).

Items that may be modified using EDIT_POINTs used to stay selected after pressing ESC (only EDIT_POINTs got away) - fixed.

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

Added possibility of switching tools by the right toolbar buttons, without deactivating the current tool first (previously tools did not switch if there was one active).

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.