Improve/extend hitsounds

[ETLegacyTeam]

Author: @IR4T4 (IR4T4)
Date: 2019-02-08
Redmine Issue: 1201, https://dev.etlegacy.com/issues/1201

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I've just remembered the current hitsound implementation is based on 'client' side (see ps->persistant[PERS_HITS]) to save resources (no extra events for hitsounds). For this the server has to count and send the updated PERS_HITS which is causing a short delay.

Hitsounds can be also done 'server' side see ETPub implementation of G_doHitSound (-> G_ClientSound -> new event)

We might change the code so both ways are available.

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Related issue(s): #507, #1200