[feature request] advanced filtering of search results based on author/library/title etc.

[vivekpn]

At times, I'm interested in searching only book titles however pustaka.sanchaya.net as of now searches everywhere. Another example of this usecase is to search for openly accesssible books such as the ones in archive.org.

We can have current behaviour of searching every field as the default option, however advanced filtering can be useful at times.

I have not checked code, if it helps I can take a look and create a pull request. Thank you!