Massfill of squares with same entities

[tronta]

In order to fill bigger areas quickly it would be great to be able to select an bigger area with the same elements.

1. Select an element type
2. Select an area with drag and drop (a rectangular border appears around the selected squares)
3. When releasing the mouse the area get filled automatically with that element type

I personally would remove the current drop down list in favor of this to simplify the interface.

[tchx84]

This should be doable, and having the ability to select chunks of entities is a prerequisite for other additions like copy and paste.