Confirmation dialog before removing all rooms.

Signed-off-by: Mariusz Fik <fisiu@opensuse.org>

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#	new file:   .idea/dictionaries/fisiu.xml
#	modified:   res/values/strings.xml
#	modified:   src/fik/mariusz/android/paintcalc/MainActivity.java
#	modified:   src/fik/mariusz/android/paintcalc/fragment/MainFragment.java
#	new file:   src/fik/mariusz/android/paintcalc/fragment/RemoveRoomsDialogFragment.java
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