API deprecation

[tmilnthorp]

Should we deprecate the following static properties from the quantities:

• BaseDimensions
• BaseUnit
• Units

These are all accessible from the Info property/classes now.

[tmilnthorp]

@angularsen

[angularsen]

• Units: I'm not so sure. The replacement would be Length.Info.UnitInfos.Select(ui => ui.Value), which is a lot more cumbersome than just Length.Units. The arrays are small so I don't worry about the memory usage either, but we could add a getter that enumerated the UnitInfos in the same way. Another alternative is to un-obsolete Length.Info.Units property, that could be a fair compromise and keep most things in one place.
• Length.Zero should still remain I think, like TimeSpan.Zero.
• Min/MaxValue are already moved and obsoleted (removed in v5).
• BaseDimensions/BaseUnit: Sure.

[angularsen]

I'll get to this soon