Better short directory names in tab titles.  Where common dir names are encountered at the end of the path, they are abbreviated to their first letter, and the search continues until a name not found in the set of common dir names is found.  eg.  '/path/to/konsole/src' and '/path/to/kate/src' are now abbreviated as 'konsole/s' and 'kate/s' respectively, instead of just 'src' in both cases.

svn path=/trunk/KDE/kdebase/apps/konsole/; revision=681390