pull charlylima:bookmarks-charly to csete:bookmarks

Csete, please consider merging my bookmarks-charly branch into your bookmarks branch. 
It improves these points: 

 *  More obvious way to edit and delete bookmarks 
    (Add a right-click menu to the Bookmarks Table with a "Delete" entry.  Make all fields in Bookmarks Table editable. The Modulation field got a combobox to select from.)

 *  Multiple tags per bookmarks 
    (currently entered as text, separated by comma, needs further improvement)
    (a problem with multiple tags is that there is a color associated with every tag, so there are multiple colors per bookmark. currently it uses the color of the first active tag.)

And also:
 * When clicking on Bookmark, also set Modulation and Bandwidth.
 * Fix errormessage "Ignoring Line" when loading bookmarks.csv. 
 * Fix error in auto selection of bookmark on manual frequency change