Removing spec proposals. Implemented elsewhere.
Setter for attribute types, checking assigned type
Check attribute type in property method
Making type list on instantiation, not on the fly
Also check types on import from hash
Specs for a few Props methods, otherwise untested
Make check work correctly with mixins
Return empty also with no kind at all
Specs for empty?() finalized
Specs for the use of mixins, other methods covered
Polishing capitalization and code dislocation
Shuffling methods around, moving initialize to top
Forgotten duplicate removed, empty?() streamlined
Exceptions polished, with specs but also TODOs
Using the Ruby way to concatenate keys
Using typed errors in check()
Merge pull request #60 from sustr4/specupdate

Checking methods in Properties