Add scripting (tengo) support for every incoming message (#731)

TengoModifyMessage allows you to specify the location of a tengo (https://github.com/d5/tengo/) script.
This script will receive every incoming message and can be used to modify the Username and the Text of that message.
The script will have the following global variables:
to modify: msgUsername and msgText
to read: msgChannel and msgAccount

The script is reloaded on every message, so you can modify the script on the fly.

Example script can be found in https://github.com/42wim/matterbridge/tree/master/gateway/bench.tengo
and https://github.com/42wim/matterbridge/tree/master/contrib/example.tengo

The example below will check if the text contains blah and if so, it'll replace the text and the username of that message.
text := import("text")
if text.re_match("blah",msgText) {
    msgText="replaced by this"
    msgUsername="fakeuser"
}

More information about tengo on: https://github.com/d5/tengo/blob/master/docs/tutorial.md and
https://github.com/d5/tengo/blob/master/docs/stdlib.md

1 files changed, 1 insertions, 0 deletions

diff --git a/README.md b/README.md
index 4ccfd9db..4923e360 100644
--- a/README.md
+++ b/README.md
@@ -282,6 +282,7 @@ Matterbridge wouldn't exist without these libraries:
 * xmpp - https://github.com/mattn/go-xmpp
 * whatsapp - https://github.com/Rhymen/go-whatsapp/
 * zulip - https://github.com/ifo/gozulipbot
+* tengo - https://github.com/d5/tengo
 
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