New command goes by LOADSC in script files and in the enumeration.
Scenarios are stored using the internal also used for localisation.
Scenarios selected can only be scenarios to originally come with one of
the games or expansions.
Modified Scenario Select window to have a mode just for title editor
scenario selection.
`ScenarioFileIndex`'s `Serialize` and `Deserialize` now read and write each
individual value of a `scenario_index_entry` instead of the entire struct
at once. Thus the difference in pointer sizes of `highscore` on different
architecture builds will not cause issues with `scenarios.idx`.
The scenario repository did not correctly handle custom RCT1 scenarios.
They were not listed, but if they existed, an empty entry would appear in the scenario list.
This fixes both issues, and also prints a warning message, should this ever happen again.
In particular, the object repository can potentially be deleted before the object manager is deleted. This causes a crash when the object manager is deleted because it requires the object repository within the destructor.
