Filter using combo box input type fails when property values contain ampersand '&' characters

[kghbln]

https://phabricator.wikimedia.org/T30790

[pastakhov]

This should be fixed in #48

[gesinn-it-gea]

Fixed in commits 6f84591 and bd4fa75 (pushed to master).

The combobox now uses data-mw-input-name / data-mw-filter-name attributes instead of the first-option-value hack. When the user selects a value from the dropdown, the JS widget switches the input name to the direct-match parameter (FilterName[N]) before form submission — the same path used when clicking a filter link — avoiding the LIKE-search path that mis-handled & and other special characters.