Added new methods to read and write settings values by type to ISettingsSection and implementation. Supported types are - Boolean, Integer, Float, Date-Time and String. The idea is that the burden of value type conversion is moved from client code into Settings object. Boolean values are now written as 'True' and 'False'.
Removed old ItemValues[] array property - now replaced by new methods above.
Removed several unused methods and properties from ISettingsSection and its implementation.
