Journalism: LevelTime

[LswaN58]

There is an existing feature named TotalLevelTime. We should rename this to LevelTime, and rewrite this feature based on the below:

This should be a per-level feature with two subfeatures. The "main" feature is the "total" time spent on the given level, which is the time from first event to last event. This is currently what is being calculated by the exiting TotalLevelTime feature. The subfeatures are the idle time (refer to existing full-session time feature, named PlayTime, for how to access the idle time) and "active" time (total time minus the idle time).

In summary:

• Main feature: no special name, calculate by last event timestamp - first event timestamp
• Idle: name Idle, refer to existing feature
• Active: name Active, calculate by Total - Idle