Halflife: [Feat. Req. HL1] Add Hudmessages Channels

[ConnorMcLeod]

To be honest, it is a 100% "for amxmodx" request, so if this is too much work, just forget it.
Else, it would be nice to have more avalaible hudmessage channels (4 actually), so more than 4 messages could be shown at the same time (16 or 32 should be enough).

[ghost]

Second for this

[fred0r]

That would be really nice

[MatiasEsf]

good idea

[Mistrick]

All HUD/dhud, saytext make huge drop client fps.
I play on specific cs mode where I need 333-500fps and 5 saytext messages can drop fps to 150-200 from 333.
Need some optimization for HUD draw and then increase channels, etc

[oaus]

@mikela-valve Can you make this possible for a future release?
8 available channel seems okay

@kisak-valve Remove the Half-Life label as this affects all modes.

[Solokiller]

Technically the existing code can support up to 255 channels without requiring a breaking change in the network message:
https://github.com/ValveSoftware/halflife/blob/5d761709a31ce1e71488f2668321de05f791b405/dlls/util.cpp#L790

The client would need to be updated to handle more concurrent messages:
https://github.com/ValveSoftware/halflife/blob/c7240b965743a53a29491dd49320c88eecf6257b/cl_dll/hud.h#L375

The engine sets up TE_TEXTMESSAGE messages by manually calling the HudText network message which is how they end up in this HUD class.

But unless the performance issues are resolved first this will result in even more FPS drops if servers start sending more messages at the same time.

Increasing the channel limit shouldn't break mods, they won't be able to display all messages (if 16 are active at the same time any additional messages are ignored) but the existing code will gracefully handle the increase.