[recognizePDF] Restructure file
Merge pull request #217 from aurimasv/recognizePDF

Tweak recognizePDF to avoid false positives
Minor documentation update
Merge pull request #221 from aurimasv/misc

Misc changes
Accept two missing letters in object keys (but don't use them yet)

Also:

- 'T' doesn't come after 'X' (but does probably appear disproportionally
  in existing object keys)

This commit has been brought to you by the letters 'L' and 'Y'.
Add lowercase 'j' to randomString() (not used for keys)
Context-menu item delete from library root didn't show a prompt