Removed IOCached

This was an unsafe abomination that falsely suggested referential
transparency. Better use `unsafePerformeIO` once in a module (object)
and at least know what it's all about.

This is a breaking change therefore the build version was set to
0.2.2.
Removed dependencies on scala.swing

IOChooser now uses JFileChooser directly. scala.swing is no longer
to be supported since it hasn't seen much activity lately.