Support of Subentities

[ironicnet]

I know that subentities are pro only. But when i tried to import one it gave me an error indicating that there is no folder -1.

The point where it fails is in the File: SpriteTimelineKey. Line 95.

this was the element that was trying to parse:
<object entity="0" animation="15" t="0" x="-1" angle="0"/>
instead of a normal entity key:
<object folder="0" file="4" x="2.470626" y="-0.905654" angle="270.567266"/>

I'll try to fix and do a pull request when i get some time.