Added properties for map objects

Also in this change:

* Made SpinBox and DoubleSpinBox don't respond to changing from
  keyboard typing immediately.

* Share a single implementation of wrapping label/widget pairs for
  SizeEdit, SizeFEdit, PointEdit, PointFEdit and RectFEdit.

* Added widget factories for QFont, QSizeF and Qt::Alignment.

* Allow setting suffix on custom FloatEditorFactory, used for adding
  degree symbol to rotation values.

A few things remain to be done:

* Custom widget for editing tile object flipping flags
* Try reducing size of font editor with style toggle buttons