Smal refactoring of negotiate commands in messages and packets, WIP:
negotiation of FPS at TCP data channel

Signed-off-by: Jiri Hnidek <jiri.hnidek@tul.cz>
WIP: Negotiation of FPS at TCP data channel

Signed-off-by: Jiri Hnidek <jiri.hnidek@tul.cz>
* Final version of negotiation of FPS on TCP data channel

Signed-off-by: Jiri Hnidek <jiri.hnidek@tul.cz>