libdeng2|SavedSession: Use Info array notation for present players in session metadata
libcommon|GameRuleset: Fix GameRuleset::fromRecord construction

When Info parses the source file it currently trashes any existing case
in key value names to all lowercase.
libcommon|MapStateReader: Fix map state value reading, added a read-float method

As of this commit it is now possible to load .save packages which have
been translated from native savegame format versions using the new
Savegame Tool.