Screenshot blocking Redux

[grrrrr]

A follow on from #114

Thank you for implementing partial blocking of screenshots. Having tested this on v3.0 I feel that it is somewhat lacking in blocking what is being read. With the Screenshot policy set to Always block for reader, this still lets the contents of what you are reading, searched, favourited, e.t.c be captured.

Suggestion would be to modify the Screenshot policy -> Always block to block all sections of the app and maybe change the Block on NSFW to Block Reader Only (or maybe drop the option altogether). Blocking all sections of the app should make this option easier to maintain as you don't have to keep track of the sections protected.