Fixes AnimationSet(std::string filename) uninitialized mFileName warning

[cugone]

Closes #962.

[DanRStevens]

So this isn't too bad. It avoids changes to the public API would that introduce XML dependencies, so that's a huge plus.

On the downside, it is adding XML code back into the class, but only in a private manner, and only affecting the implementation file.

I feel like I might want to play with this a bit and see if we can get something better.

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Related, the resource cache code relies on constructors. I had considered looking for ways to extend the resource cache code so it could alternatively use factory functions. Perhaps extend the template and give it a default factory function that delegates to the class constructor. I never put in the time to figure out the syntax though.

If we could update the resource cache code, there would be little reason to maintain a constructor that reads from a file. Particularly not if we want to remove dependencies on file parsing libraries. Instead, that can be moved to a factory function, such as already exists, and have the resource cache code use the factory function. That would enable us to lift the factory function out of the library into the executable project, along with dependencies on specific file processing libraries.

[DanRStevens]

I don't know if I'm quite ready to review this one yet. This one ties in with issue #972.

[DanRStevens]

Closing this to go with a hybrid solution in #1003.

Both solutions were similar, in that initialization was moved to the constructor body, rather than attempting to use the constructor initialization list. That was the key factoring in removing the warning. The other solution keeps most processing in functions in unnamed namespaces, whereas the solution here moved some XML code into the constructor, while leaving the corresponding function from the unnamed namespace intact but uncalled.