Center map optimalisation

[roelderickx]

Currently the track on a given page is centered, either horizontally for landscape or vertically for portrait orientation. In some cases there are other tracks on the page, centering the track we're currently processing is not always the most optimal decision.
The page boundaries should be chosen so that:

• The part of the track we are currently processing is still on the page
• A maximum of other tracks are also on the same page

Implementing this will replace the need to check all track permutations.