libkate: Format - data packet type 0x01 - keepalive

# Format - data packet type 0x01 - keepalive

Keepalive packets may be inserted at any point in a Kate stream where a data packet may be inserted (eg, after all headers, and before the end packet).

Keepalive packets are meant to help seeking code by placing packets at regular intervals so a seeking program can keep track of the granulepos without having to seek too much.

It is not mandatory to use keepalive packets, but their use may improve seeking performance on a Kate stream with few events when it is multiplexed with high bandwidth streams.

This packet is exactly one byte long, and consists of its packet type byte, 0x01.