Usage: add in halflife.fgd:
```
@PointClass base(Targetname) = trigger_command : "Trigger: Command"
[
	netname(string) : "NetName"
]
```
After creating the trigger_command point entity,
you give it a name and NetName for console command.
After that, create a brush with trigger_multiple
and in target specify the name of the entity of your trigger_command.