[ADC] Implementations send/require BAS0

[Fredrik Ullner]

Many implementations send and require the feature BAS0. This feature does not exist officially and was the feature before BASE was finalized and released.

All implementations (client and hubs) should first remove the validation.

If a hub can omit sending BAS0 during C-H, it should do so (unless clients require it - needs investigation).

If a client can omit sending BAS0 during C-C, it should do so (unless the other party require it - needs investigation).

Implementations should omit sending BAS0 once 'all' implementations does not validate/require it.

[Fredrik Ullner (ullner)]

DC++ does not require BAS0, but it will treat BAS0 as if one sends BASE and TIGR at the same time.

ADCH++ does not at any point check for BAS0.

[Fredrik Ullner (ullner)]

ncdc does not send or use BAS0.

Luadch sends BAS0 according to https://github.com/luadch/luadch/blob/master/core/hub.lua but it seems to be a fallback.