commitmonitor Code

Don't try to convert a date string if the string is invalid.
This fixes issue #34.

Update to r29004 of the Subversion trunk and adjust the changed API calls.

Update to r28878 of the Subversion trunk and adjust the code according to the API changes.

Update to r27993 of the svn trunk.

Indicate the GPL license.

Initialize the pointer to the progress dialog.

Clear the Subversion errors after we don't need them anymore.

Use the end revision as the peg revision.

Make sure that temporary files are removed after using them.
(I had over 13'000 temp files from the CommitMonitor in my temp folder before I noticed this. Yikes!)

* Add wrapper class for IProgressDialog
* Add callback for the progress dialog.