Plugin mechanism is not working as in PIL 1.1.7

[ignaciordc]

It seems that the mechanism to extend Image plugins is different in Pillow.

With PIL 1.1.7 I wrote my own image plugin, that I would call xxxImagePlugin.py
The code in that plugin would ´register´ the extension of my new Image format, say ´xxx´.

I would call Image.open(´myfile.xxx´) and there I had it.
Now, _plugins[] is initialized in init.py and there seems to be no further checking of the new image formats.

Interactively, I was able to modify the source and reload it, to observe changes as I was developing it, whereas now the _plugins is obscured in the namespacing convention...

It may make sense this change, but should be documented more clearly

[wiredfool]

There were several reasons that change was made, and documentation would help. If you've got the proper registration function calls in your file, simply importing it should be enough.