Implement searching from alternateClassNames.

Changed search records structure around a bit:

- "type" field is now either "class" or "member".
- new "icon" field defines the icon to show.
- "id" is defined for each record and identified the search result.
  For example the id of alternateClassName record is the name of
  the original class.
- simplified the code a bit in the filterMembers method that
  performs the actual searching.

For alternateClassNames we show the subclass icon.
Should be good enough for now.