Spring version used not stated in replays

[Gpox]

The version of spring source used in a recording is not stated in the content of the replay the same way as other data is. It can be found from the default name of the file, but filenames can easily be changed. As the version is a major factor in classifying games and assessing whether they can actually be watched, it would be best if this key-value pair could be added to the start of the replay data in future versions.

This problem arose from the need to dig up the game data for sorting at fu in thread: http://taspring.clan-sy.com/phpbb/viewtopic.php?t=2602