Log Message:
snapshot-20100523 of eric4 released. It fixes some bugs and includes these changes.

*  added code to use the PYTHONPATH environment setting in the debuggers
* added code to indicate directories and files being symbolic links
* added code to save the editor zoom factor in the session file
* added code to update the file browser window (mostly) automatically
* added code to update the Others tab of the project browser (mostly) automatically
* added a menu to the highlighting styles config page to change individual \ 
aspects of a font only
* added code to show the keyboard shortcut to the tooltip of an action
* changed the Find in Files dialog to remember the history of the search string, \ 
replace string and the search directory
* added code to enhance the proxy configuration and removed the usage of QHttp