* changing orientation no longer causes loss of data.
* Brought back support for icons on buttons, but as they look ugly at
the moment, the code is commented
* Window for properties edit is introduced. Now it shows only prop
names, loaded from Preset corresponding to POI. Disappears in 5 secs
+ Added ok button to close props window. TODO: reset timeout timer
Preset classes reworked to support text notes (and adding audio notes
will be easy)
Propwindow shows for both POIs and TextMarkers