Too many options that control saving behavior

[MSeeker1340]

The output control options in http://docs.juliadiffeq.org/latest/basics/common_solver_opts.html are all individual fields within DEOptions. Furthermore there's the force_save parameter in savevalues! and save_positions for callbacks. Adding to that the precedence of the options are not well documented and sometimes hidden.

I think it's best we tidy up and consolidate all saving related options into a SaveOption. We can still keep the simple kwargs style in solve but internally interface SaveOption for better organization.

[ChrisRackauckas]

Note that moving options is breaking to existing code. We'll need to deprecate any moved opts via getproperty overloading.