unified calibre plugin (#6177)

joins calibre metadata search and calibre wireless connections into a single plugin

search metadata changes:

- search directly into calibre metadata files.
- search can be performed on more than one library (configurable from a menu)
- device scans now find all calibre libraries under a given root
- search options can be configured from a menu. (case sensitive, find by title, author and path)
- removed legacy global variables.
- *option* to search from the reader
- *option* to generate a cache of books for faster searches.

calibre wireless connection changes:

- keep track of books in a library (includes prunning books from calibre metadata if the file was deleted locally)
- remove files on device from calibre
- support password protected connections
- FM integration: if we're in the inbox dir it will be updated each time a book is added or deleted.
- disconnect when requested by calibre, available on newer calibre versions (+4.17)
- remove unused opcodes.
- better report of client name, version and device id
- free disk space checks for all calibre versions
- bump supported extensions to match what KOReader can handle. Users can override this with their own list of extensions (or from calibre, by configuring the wireless device).

frontend/ui/elements/reader_menu_order.lua

@@ -114,7 +114,7 @@ local order = {
     },
     tools = {
         "read_timer",
-        "calibre_wireless_connection",
+        "calibre",
         "evernote",
         "statistics",
         "progress_sync",
@@ -149,6 +149,7 @@ local order = {
         "----------------------------",
         "goodreads",
         "----------------------------",
+        "find_book_in_calibre_catalog",
         "fulltext_search",
     },
     filemanager = {},