Before, even though we did match all possible extensions,
we only took the first match and tried opening it.
If we were looking for a .png image, but there was an unrelated
.txt file with the same name (as it actually happens in RTPs),
we would potentially see the .txt first, try opening it,
and fail alltogether, even though the image file existed.
Now we try opening all matching files until we find one that
we can parse.
This fixes#101.
Previously, file lookup (ie. extension supplementing) would only
try out a few predetermined extensions based on the asset type.
This was not accurate in regard to RMXP's behavior, which will
happily match "some_asset" against "some_asset.abcef" and try
to open it.
Some games make use of this quirk and rename their ogg audio files
to "*.dat" or similar to thwart users from copying them.
This change also makes it easier to read arbitrary formats
supported by SDL_image without modifying mkxp.
If no source is free, instead of seizing the lowest priority one,
first try to find the lowest priority source with the same buffer
that is about to be played and use it. Otherwise, take lowest priority
one as before.
Jonas Kulla