Template parsing does not work

[benni-tec]

Current bug behaviour

The TiledObject.parse() function tries to find a <template> child of <object>. However according to the TMX Documentation and the dartdoc comment above the class such an element is not allowed as a child.

Expected behaviour

Tiled uses the template reference in the template attribute of <object> to find the external template file. Maybe a lookup mechanism like TsxProviders is needed.

More information

Together with the extension to TsxProviders in #70 it might be worth generalizing a Provider for Tsx, template files and images.
I would be interested in working on a PR for this, however I do not need this functionality atm, so I wouldn't get to it for a few weeks.

[spydon]

I'll assign you to it meanwhile