Added 24x24 version of btn_icon_create_new_case.png
Added improved version of btn_icon_create_new_case-24.png
Possible solution for IllegalStateException due to redundant associateLookup() calls
Eliminated redundant calls to assocaiteLookup() in DataResultTopComponent
Removed 24x24 version of 'New Case' icon
Merge pull request #255 from rcordovano/explorer_lookup_fix

Eliminated redundant associateLookup() call in DataResultTopComponent.componentOpened().