[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.
[12597] Fix aura not removed in some case. ProcFlag test seem not enough in some case.

Fix #307