Added PCBNEW_CONTROLS for handling miscellaneous hot keys (trying to be compatible with the default hot key settings). Currently there are a lot of stubs to be filled out (in pcbnew_controls.cpp).
Handled actions:
- switching layers
- switching grids
- changing track width & via size

ROUTER_TOOL events have temporarily changed their hotkeys assignment.

Removed EDIT_CONSTRAINT::Update() - replaced with resetting constraints.
EDIT_CONSTRAINT is stored in EDIT_POIN using boost::shared_ptr instead of pointer.
Added EDIT_LINE::GetEnd() & GetOrigin(). Overridden ApplyConstraint() for EDIT_LINE.
Side EDIT_POINTS for zones are drawn as circles.

Switched order of EDIT_POINTs for DIMENSION, so in case when feature lines are of 0 length, then still can be stretched.

Dimensions have EDIT_POINTs.
Different handling of 45 degree mode in POINT_EDITOR.

Added a few settings to make the layer settings more similar to KiCad defaults (moved vias to VIA_THROUGH_VISIBLE, added a few rules for required layers).

Added POINT_EDITOR::isModified().

Minor code cleaning.

EDIT_POINTs show up when there is only one item selected (now after deselection as well).

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

TOOL_EVENT message is supposed to contain string as parameter.
Added missing header for class_drawsegment.h (KiROUND).
Renamed SELECTION_TOOL::containsSelected() to SELECTION_TOOL::selectionContains().