[Enhancement] add full text search option to advanced search
At present calibre's advanced search only searches the metadata of ebooks. This is great if the metadata exists, but not very helpful if you're trying to figure out which books need metadata added to them. Adding a full text search option would allow people to more easily determine what books contain a significant keyword (or phrase), select those books, and then add the desired metadata all at once.
Here's some of the situations I've come across where such a feature would have made my life easier:
* The series title is not included in the embedded metadata. This is problematic if I add many ebooks to calibre at once (which I usually do) and I cannot recall which books belong to the series in question.
* The website I most frequently download ebooks from has a lot of useful metadata included in the preface of the ebook, most of it standardized enough that I like to add the content as tags, which is how I typically find what I want on my ereader. You do not want to know the obscene number of hours I've spent manually adding these tags.
* I have 2000+ ebooks in my library. I like to add tags for specific genres, which could be easily identified by full text searching (for "Paranormal", I could search for magic, werewolves, vampires, etc.).
Some formats would probably lend themselves better to full text searching than others. If I needed to convert all my epub to html or rtf, that what I would do. Metadata I can use is vital to me.