[Jslib] jslib check-ins and troubles

[Martin Kutschker]

Hi!

I've checked in some fixes for minor glitches and added a way to get 
alerts for debug and error messages. See bugs and cvs checkins for details.

I have also noticed (as prosted before) that urlToPath and chromeToPath 
(fileUtils.js) are broken on Windows and probably on Mac as well. Please 
folks, remember URL paths are NOT valid local paths on Windows and Mac!

I repeat my proposal to add a toURL() method to the Filesystem class.

Masi