* Added support for Targa files.
* Code re-organised to allow for easier additions of new file formats.
* Spaces in layer names are changed to '_' and not eaten anymore.
* Script changed to run only on hitting the 'Continue' button.
* script renamed to match the built-in version closer;
* GUI definition moved to an external file 'dialog.json';
* minor clean-up in the organisation of the script
* original functionality restored
* Documentation updated.
* Added selection of destination folder.
* Implemented generic layer traversal.
* added ignore filter for testing files
* comments improved
* layer count fixed
* Implemented export of visible layers.
* Re-implemented export of all layers.
* Speed tests performed, results recorded.
* Added in-code profiling capabilities (ExtendScript Toolkit for CS2 is unreliable).
* Further speed-up of exporting process achieved; export algorithms merged. (Indexing layers through API is very slow.)
* Collecting layers delayed until a later stage, so the dialog appearance is snappier.
* Requirement for the document to be saved and be a layered PSD lifted.
* Documentation updated; tests run against this major version.
* Fixed missing options in CS5 or later.
* Fixed restoring layer visibility for newer PS versions; reverting history trick doesn't work there.
Merge pull request #8 from skjorn/master

Added support for Targa files.
Cleaner and more informative UI
More maintainable code