Basic plugin system

[S-S-X]

Transform most "core" chat functionality into isolated extensions and uses single entry point for chat message handling.
Closes #18

These are moved, check after tested

• pm @player hello world and /msg player hello world
• whisper $ hello world and $50 hello world
• hash #channel and #channel hello world
• me /me hello world

Todo

• Requires merging changes from Allow colorizing chat messages on selected channels #32 or will crash during loading
• Remove on_mods_loaded hack from default message handler

[S-S-X]

Whispering $150 Hello world works but also prints command to chat so result what players see is
|#main| <SX> whispers: $150 Hello world
It should drop $150 from message.

[S-S-X]

Noticed that this also fixes case where whisper radius is more than max radius: in addition to error message whole chat line was printed to main channel.
This PR seems to fix that too to not print to main if radius is larger than max and will correctly still print error message.

[S-S-X]

Also fixes on_receive callback possibly executed multiple times in certain situations, so far nothing got actually affected by this but there's no reason to go through it more than once when message is received.

That on_mods_loaded hack must be fixed or error removed from end of main message handler in router.lua, before that is done if player without shout privilege send message it will crash server with Beerchat was unable to handle message: .... Added that error just for easy testing if anything falls through.

[S-S-X]

Some code changes to whispering, tested functionality again and seems to work just fine.
Everything seems to be fine.

@BuckarooBanzay how does structure/changes look for you? Good enough?

My personal opinion: Even while this is not bringing complete API or automated plugin loading I think this is better for development than everything in large pile.

[BuckarooBanzay]

@BuckarooBanzay how does structure/changes look for you? Good enough?

they involve a bit more "magic" than just plain dofile calls but that will work in this case 👍

My personal opinion: Even while this is not bringing complete API or automated plugin loading I think this is better for development than everything in large pile.

Better something imperfect now than something perfect someday :)

[S-S-X]

Then sounds good enough 😄