DbicAppCombo2: sort first by match type - fixed #83

When the combo list is filtered accoring to a type_filter_query a
pre-sort is now applied according to the type of match: exact matches
first, followed by matches at the start of the string, followed by
everything else (i.e. matches anywhere within the string). The original
sort (default alphabetical) is still applied within each of the 3
possible groups.

(set dev version 0.99501_03)