Dimensions calculation is errorneous

Currently Dimensions calculation works only correctly when map object requested is smaller than actual map size.

we need to introduce smarter code that can better handle extreme cases such as:

1) correct map centering on even number map length
2) correct off-the-map corner case correction (snap to a side of the map instead of going off the map if centering point is closer to the map border than the actual map center)
2.1) this also needs to take into account if we request map boundaries that are bigger than the map itself.

in short: need smart map size correction, even number map length centering, map edge centering correction.