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).

defaults.lua

@@ -224,22 +224,23 @@ FRONTLIGHT_SENSITIVITY_DECREASE = 2
 -- insensitive sort
 DALPHA_SORT_CASE_INSENSITIVE = true
 
+-- no longer needed
 -- Set a path to a folder that is filled by Calibre (must contain the file metadata.calibre)
 -- e.g.
 -- "/mnt/sd/.hidden" for Kobo with files in ".hidden" on the SD card
 -- "/mnt/onboard/MyPath" for Kobo with files in "MyPath" on the device itself
 -- "/mnt/us/documents/" for Kindle files in folder "documents"
-SEARCH_LIBRARY_PATH  = ""
-SEARCH_LIBRARY_PATH2 = ""
-
+--SEARCH_LIBRARY_PATH  = ""
+--SEARCH_LIBRARY_PATH2 = ""
+--
 -- Search parameters
-SEARCH_CASESENSITIVE = false
-
-SEARCH_AUTHORS = true
-SEARCH_TITLE = true
-SEARCH_TAGS = true
-SEARCH_SERIES = true
-SEARCH_PATH = true
+--SEARCH_CASESENSITIVE = false
+--
+--SEARCH_AUTHORS = true
+--SEARCH_TITLE = true
+--SEARCH_TAGS = true
+--SEARCH_SERIES = true
+--SEARCH_PATH = true
 
 -- Light parameter for Kobo
 KOBO_LIGHT_ON_START = -2           -- -1, -2 or 0-100.