caching options, async task

[yeago]

[dokterbob]

First of all, thanks for your contribution! :)

Generally, your patchset is clearly awesome in the features it composes. Though rather then just simply merging it without letting other users know: it might be good to write a few lines about the availability of and the usage of the new features in the README.

As soon as this is done, and the few issues I mentioned are fixed I would be more than happy to merge them in.