Configuration values are internally stored as CoreEntry
For null entries now uses CoreEntry.NULL_ENTRY (Removes the NULL_PLACEHOLDER etc)
Removes the specialised propertiesBoolCache, CoreEntry parses boolean value once
Changes behavior such that get(key, default) stores an entry. This makes this consistent with how the boolean entries worked. Changes the test at: ConfigTest.get_default_repeated_expect_returnDefaultValue
get(key, default)stores an entry. This makes this consistent with how the boolean entries worked. Changes the test at: ConfigTest.get_default_repeated_expect_returnDefaultValue