MapRenderer: Do not call map_to_screen so often for Orthogonal maps.

Fixes #326 for orthogonal maps.
Add option for equipment to apply when transformed

In response to #448

With this, we can now use `keep_equipment=true` for flare-game's Stealth
power. The default value for this false to retain the old behavior and
avoid breakage with other games.
Increase the size of the dot showing the hero on the minimap.
Don't invalidate iterators again!
Merge pull request #459 from stefanbeller/largerheroonminimap

Increase the size of the dot showing the hero on the minimap.
Merge pull request #458 from dorkster/bugfixes

Add option for equipment to apply when transformed
Merge pull request #457 from stefanbeller/speeduprender

MapRenderer: Do not call map_to_screen so often for Orthogonal maps.
Merge pull request #460 from igorko/master

Don't invalidate iterators again!
Merge branch 'master' of https://github.com/clintbellanger/flare-engine