Protocols revision

[si14]

We need to revise distribution of methods between protocols at some point. Here is an example why this is needed:

(defprotocol PZeroDimensionAccess 
  (get-0d [m])
  (set-0d! [m value]))

(defprotocol PZeroDimensionSet
  (set-0d [m value]))

There is no semantic reason why this two protocols should be different.

[mikera]

Agree some of these can be merged

We need to do so judiciously:

• Changing protocols will break core.matrix implementations in most cases
• Bigger protocols mean that implementers have fewer degrees of freedom when choosing which protocols to implement