[PATCH] Adapt replays for variable turn length

[elexis]

This ticket deals with adapting the replay menu to variable turn lengths (#3752, #69).

Reading the entire commands.txt file to derive the total game duration of a replay is an I/O-heavy task, as the previous iterations of the patches in #3258 had shown.

If #4020 can be solved, the duration could be loaded from metadata.json, where it is saved as timeElapsed.

[elexis]

(rewrote the ticket as commands.txt is very likely the wrong place to save that information)

[elexis]

Variable turn lengths: The patch still uses getReplayDuration which doesn't work with variable turn lengths. Since there is a feasible approach to keep constant turn lengths with ensuring that the simulation isn't paused due to network lag, it might not be needed to adapt it to variable turn lengths.

If #3752 is settled and fixed this might be reopened.

Performance: I doubt whether it is really faster to load and parse an entire JSON file instead of doing what is done now. The commands.txt file is already opened and getReplayDuration only reads the last few lines. The metadata file is only opened when selecting a replay, not when getting the replay list. So the attached patch opens a second file instead of only that one for every file in the replay list. The duration should be saved to the replay cache though.

Code style:

• Only one hunk adds relevant code. The others should be part of a cleanup commit that changes all occurances (i.e. GetReplayAttributes too).
• L251 should be an else since there might be a replay with duration 0. Don't be so negative and invert the condition of the if statement.
• Use ScriptInterface.GetProperty instead of JS_GetProperty