use Exception instead of IOException on LRU cache methods
Merge pull request #149 from moagrius/issue-147

use Exception instead of IOException on LRU cache methods
adding new moveMarker signature, updating existing signature
reformat
reformat
Merge pull request #150 from moagrius/issue-148

Issue 148
removed isEmpty fast-fail per #141
Merge pull request #151 from moagrius/issue-141

removed isEmpty fast-fail per #141
Ensure that we always load bitmaps (even assets) on a background thread.

When that is done we can call postInvalidate to signal from any thread that this view needs to be redrawn.