[Enhancement] Search enhancements
I have some enhancements that I feel would improve usability in calibre:
1) Allow for an auto-highlight for the previous search term when I click on the search bar.
2) Allow for automatically adding quotes when pasting to the search bar
3) Automatically select and highlight books in the cover grid when typing outside the search grid. e.g., I type L and it scrolls down and highlights the first book title starting with L
4) Have a separate thread for searches so that it doesn't completely freeze the UI when executing a search