Misc Fix-ups: to 2D Mapper

T2DMap.cpp: Moved several #includes to top of file and organised them.

T2DMap::paintEvent( QPaintEvent * ): missing break; inserted.

T2DMap::mousePressEvent( QMouseEvent * ): unified a pair of Status tip messages.

Added missing 2D mapper context menu item: unlock selected room(s), new method
T2DMap::slot_unlockRoom() created.

Added additional custom line styles to TLuaInterpreter::addCustomLine() .

T2DMap::slot_deleteCustomExitLine(): removal of line did not clean up some items in
TRoom class instance.

T2DMap::slot_spread() & T2DMap::slot_shrink() : detecting and skipping another
no-action case.  Corrected dialog box text in latter copied from former but not
modified and revised both.

T2DMap::wheelEvent( QWheelEvent * ): accommodate the depreciation of
QWheelEvent->delta() method in Qt5.

Signed-off-by: Stephen Lyons <slysven@virginmedia.com>