MAP: changed tracing to line

trace is now line. it needs to be fixed so that it's behind
the roomba-triangle and velocity-vector
MAP: bounding rectangle and visibility corrections

- The bounding rectangle of mapScene_ is now set to be mapQGraphicsView's
  childrenRect().
- curPoint_'s and curSpeed's ZValue is set to be 1 after
  adding new items.
MAP: POI's state changeable by clicking. Removal changed.

- POI's state can now be changed to red by clicking it and changed back
  to black by reclicking.
- Removal changed to apply to red POIs only
MAP: bugfix to clearRedPois

Erasing red POIs caused program to crash sometimes due to incorrect
pointer removal and delete order
MAP: added removable walls

- now by doubleclicking with right mouse button you can add the start and
  end points of a wall.
- the wall turns red with single click.
- red walls and POIs can be removed with button "Remove red objects"
MAP: reworked starting point and added "Reset angle"-button

- starting point can now be selected and removed. Removing it causes all
  tracking to be reset and removed from map except for angle_-variable. Angle
  can be reset with a dedicated button.
- some minor cosmetic changes and a tracing bugfix
MAP: added interactive scaling

- Map's width in the real world can now be set in cm and applied
  anytime.
- Roomba's triangle and trace is now at realistic size.
MAP: Fixed distance scaling
MAP: reworked mapQGraphicsView and added DISTANCECORRECTION

- The scene for the map is now made inside mainWindow instead of
  mapQGraphicsView
- added DISTANCECORRECTION -constant (both distance and angle given by roomba
  seem off)
- POI position initializing  reworked. It's now readable with pos().
SERIAL: Implemented RoombaSerial to work with iRoomba interface
UI: Mainwindow elements changed from .ui to .cpp
UI: Cleared .ui designer xml file
UI: Removed all Serial debug functionalities from MainWindow
UI: Added easy backwards driving
UI: Improved keyboard releasing
MAP: Fixed scaling parameters to avoid negative values

Coordinates start now from lower left corner. And size is fixed
to 400, 400.
MAP: Removed negative scaling of GraphicsView
MAP: POIs get removed when other item collides with them

For example, if roomba goes over a POI, it gets removed.
Also if a wall or another POI is created too close, the old POI gets removed.
Merge branch 'JuhaniJ/jj_map' of https://github.com/joonaspessi/rotfl into jj_map

Conflicts:
	src/ui/mainwindow.cpp
	src/ui/mainwindow.h
	src/ui/mainwindow.ui
	src/ui/mapQGraphicsView.cpp
	src/ui/mapQGraphicsView.h