Also upgrade the file picker filters with the new extensions found
in the orginal file picker code of Singularity.
Also improve AIFilePicker a bit: added hasFilename() and now
deleting the statemachine automatically by default: it's no longer
needed to call deleteMe from the callback.
This is the skeleton needed to implement classes that can be reused and
work together, which can perform asynchronous tasks (read: need to wait
for certain events before they can continue).
An example would be the task of waiting for a given inventory folder to
be read. This could then be used to improve the builtin AO
(automatically reading that folder when a notecard is dropped, and
continuing when the whole folder is read).
It's first use will be communication with a filepicker that runs
in a plugin.
