"Negative" search implemented

When using the guided_search function, you can now exclude certain rows by placing a "-" in front of the search word. The input "mouse, -mito" selects all rows that do not contain the word "mito" but the word "mouse". First the rows containing the word "mito" are removed, then only the rows containing the word "mouse" are kept. This works for certain columns as well as for the search in all columns.