TODO:
 . fix popup menu not being shown on first click
 . show text excerpts and meta information
 . remember last chosen search method and fulltext state
 . settings dialog
 . drag'n drop of filenames
 . add an 'update index' button
 . add filter for executables/ desktop files
 . search for files by date
 . fix occasional broken pipes
 . optional plain command line mode
 . add about dialog
 . customizable search methods
