Fix exception when sorting catalog item 'contents'

If no row was actually clicked (clickedRow == -1)
Use Case Insensitive sorting for catalog 'contents' view
Fix resolving aliases as well as symlinks in QSDirectoryParser
Comments on resolveAliasAtPath and better readability
Add Core Support Unit tests
Fix a bug in alias resolving when the URL is a symlink *and* alias
Add core support tests to the 'run all tests' target
Merge pull request #1882 from quicksilver/catalogFixes

Catalog fixes