Merge pull request #3 from heinermann/master

merge changes for public release
update license headers to include source file contributers on a per-file basis. updated namespace of editor, editorhelpers, editorsettings, undomanager to reflect their position in the folder hierarchy
improved log output when frames fill is missing
Partial work on asset refactoring
Merge with upstream
Load assets on program start and persist them globally. Completely reworked object/tile asset handling(WIP).
Include missing files