Tidy the FD plugin.

- Remove strict escape option as turning it off seems to offer no
  benefit and is a bit scary.

- Switch to using HTML escaping provided by Guava.

- Use an array instead of a crazy inefficient list that's converted.

Change-Id: Icfa1dc04fdab1c2d98c7abb15f2acd50f07c82ee
Reviewed-on: http://gerrit.dmdirc.com/3409
Automatic-Compile: DMDirc Build Manager
Reviewed-by: Greg Holmes <greg@dmdirc.com>
Also remove the setting from the UI.

Change-Id: Ib4155d36da290af7421f67505f23f907b2766897
Reviewed-on: http://gerrit.dmdirc.com/3410
Automatic-Compile: DMDirc Build Manager
Reviewed-by: Greg Holmes <greg@dmdirc.com>