Add BuildChatPacket comment, reorder parameters, correct a little bug gm name not showed on general channel (Thank to @Shauren for pointing).

Signed-off-by: Salja <salja8840@gmail.com>
[12594] Fix LANG_ADDON use on Guild Channels and avoid a possible crash.

Part of @rsa work too.
[12595] Imrpove readability of the code and avoid visual studio warning c4996 I don't think this can cause trouble with gcc but let me know if its the case.
[12596] Avoid last Visual Studio warning.