Voice transport negotiation and AES-256-GCM#4824

Draft

TerryGeng wants to merge 5 commits intomumble-voip:masterfrom TerryGeng:capabilities

+1,296-233

Commits on Jul 13, 2021

FEAT(protocol): Add Capabilities message to conduct voice protocol negotiation.
TerryGeng
committed
REFAC(crypto): Variable crypto head length
TerryGeng
committed

Commits on Jul 20, 2021

FEAT(cipher): Add AES-256-GCM as cipher of UDP voice transport
TerryGeng
committed

Commits on Jul 21, 2021

REFAC(protocol): Increase the flexibility of the VoiceProtocol and Cipher mechanism,
TerryGeng
committed

Commits on Jul 22, 2021

FEAT(cipher): Generalize EVP interface, add CHACHA20-POLY1305.
TerryGeng
committed