Added invalid file type check to batch convert and completion message.

Fixed bug preventing indexed PNGs from being imported

Added additional logging to try to resolve a bug when starting ZSprit…

…eTools by opening a file through explorer

Fixed palette loading on png import

Fixed animation sprite layer draw order

Fixed broken tests

Create ISSUE_TEMPLATE.md

Create CONTRIBUTING.md

Made animation area larger to fit Throw Up animation (in preparation …

…for adding items to animations)

Fixed animation drawing so flipped tiles are actually flipped

Added ability to set animation preview background color