* Updated Grid API
Added Nonull/Nullable/Nonnegative where applicable.
Deprecated unused methods
Changed concrete classes with interfaces (HashMap -> Map)
IGridTickable will no longer accept null as TickingRequest. Do not
implement it, if it should not tick.
* Renamed parameter to match conventions
Reduces the visibility of all fields to private and create setters/getters
when necessary. Exceptions are fields with GuiSync as these need to be
public.
Reduces the visibility of internal methods to private/protected/default when possible.
yueh