More concise search interface

[nbachiyski]

Current: even though the search interface doesn't include all searched fields it takes a lot of space and is hard to use, because of all of the clutter.

Expected: it should be easy to search for specific field values.

Implementations:

1. Having a default search bar and interface for adding more filters. Similar to http://trac.glotpress.org/query This is very powerful interface, but if you often need to search for a non-default field you will have to make 4-5 clicks/selection choices until you are ready with your search.
2. GMail-like search with only one search field and operators, which you can use inside it. Example search query: filename:wp-admin/includes status:untranslated post. The problem here is remembering all the operators, but this problem can be solved with better auto-completion, which understands our format and suggests operators and their possible values.

Both good ideas, but also using the word search instead of figuring out that Filter > Terms is supposed to help you search through the translated strings.