Filter responses and more filtering control

[jagerman]

This builds off PR #129 for language filtering, but revamps how languages are specified and overridden with a mechanism that we can use in the future for other room-specific settings, and that doesn't rely on room ids (but rather tokens).

Most notably, this PR (in addition to the language filtering added in #129) adds an ability to send responses to filtered messages either back to (just) the user who sent them (via a whisper), or to the whole room.

This allows configuration of the message (or multiple messages, for random selection), profile name, and uses a (simple) templating mechanism for the message so that you can (somewhat) personalize it for the user.

Other changes included here:

• You can now control whether or not mods/admins are affected by filtering via a new filter_mods setting. (This is particularly useful for testing, but SOGS operators might also want to restrain their mods).

• profanity filtering can be room specific.

• alphabet filtering can be room specific (revamping how PR Allow rejection of postings written in a particular alphabet. #129 did room-specific settings).

• alphabet filtering can be configurably silent or not, like profanity filtering.

• added a new, separate example .ini file showing how to set things up with room-specific settings.

Copying from the added sogs.ini.filter-sample file for the detail on how the room-specific settings and auto-reply get configured:

;
; Room-specific filtering
;
; To set filtration rules for a specific room you add a [room:TOKEN] section and then set the
; rules that should apply to this specific room.  For example, to enable the profanity filter and
; disallow (only) cyrillic characters in the room with token 'sudoku' you would add:
;
;[room:sudoku]
;profanity_filter=yes
;profanity_silent=yes
;alphabet_filters=cyrillic
;
; This overrides the default from the main [messages] config section for any given keys, so it can
; be used to replace or change the rules that apply to a given room.  Currently only the
; profanity_filter, profanity_silent, alphabet_filters can be overridden in this way.

;
; Filtration responses
;
; When a message is filtered because of the profanity or alphabet filtrations SOGS can optionally
; send a reply in the room; this reply can either be visible to everyone, or just to the specific
; user.  To enable such a reply, add a filter section here: the section name consists of
; 'filter:TYPE:ROOM' where TYPE and ROOM are the filtration type and room token, or '*' to match all
; types/rooms.
;
; Section names for all filtered messages:
;[filter:*:*]
;
; Section names for a particular filtration type:
;[filter:*:profanity]
;[filter:*:alphabet]
;
; The "type" can also be a specific language:
;[filter:*:arabic]
;[filter:*:cyrillic]
; etc.
;
; Room-specific filtration section names:
;
;[filter:fishing:*]
;[filter:sudoku:profanity]
;
; If using both '*' and specific values, the value from the more specific section will be used where
; present.
;
; Within this section there are currently three settings:
;
; - reply -- the body of a reply to send (see details below).  If omitted or empty then no reply
;   will be sent.
; - profile_name -- the profile name to use in that reply.
; - public -- whether the reply should be seen by everyone or just the poster.  The default is 'no'
;   (i.e. only the user will see the reply).
;
; The `reply` value should be specified on a single line of the config, and supports the following
; substitutions:
;
; \@ - the profile name, in @tag form, of the poster whose message was declined.
; \p - the profile name in plain text.
; \r - the name of the room
; \t - the token of the room
; \n - a line break
; \\ - a literal \ character
;
; You can also randomize among multiple responses by specifying multiple lines in the config: each
; additional line must be indented in the .ini file to be properly recognized.
;
; For example if you use this config:
;

[messages]
profanity_filter=yes
profanity_silent=yes
alphabet_filters=arabic cyrillic
alphabet_silent=yes

[room:sailors]
profanity_filter=no

[filter:*:*]
profile_name=LanguagePolice
reply=Hi \@, I'm afraid your message couldn't be sent: \r is English-only!

[filter:*:profanity]
profile_name=Swear Jar
reply=Whoa there, \@!  That language is too strong for the \r group!  Try the Sailors group instead.

[filter:sudoku:profanity]
profile_name=Bot45
public=yes
reply=\@ got a little too enthusiastic today with their solve.  Maybe someone can assist?
 Uh oh, I think \@ has two ３s in the same row!
 I think \@'s sudoku broke 😦

; then arabic/cyrillic/person would be blocked everywhere, profanity would be blocked everywhere
; except the 'sailors' room, and when a message is blocked you would get a message such as one of
; the following depending on the room and the rule applied:
;
;
; (LanguagePolice)
; Hi @Foreignsailor1988, I'm afraid your message couldn't be set: Salty Sailors is English-only!
;
;
; (Swear Jar)
; Whoa there @87yearoldgrandma!  That language is too strong for the Cuddly Kittens group!  Try the Sailors group instead.
;
;
; (Bot45); [one of the following would be sent randomly, visible to everyone in the group]
; @87yearoldgrandma got a little too enthusiastic today with their solve.  Maybe someone can assist?
;
; Uh oh, I think @87yearoldgrandma has two ３s in the same row!
;
; I think @87yearoldgrandma's sudoku broke 😦