Can now use '!' at the start of a search term to do a NOT; e.g. the search term
'!Load' will find all records EXCEPT ones containing the word 'Load'. This can
be combined with the '|', so '!Load|toner' is the same as "everything except
'Load' or 'toner'".

Created two new String methods ('condition' and 'where') to cleanly handle the
negation search operator described above.