Fix transpose for arrays

[andreasnoack]

I have failed to convince @StefanKarpinski and @JeffBezanson in #9170 and that pr is therefore superseded by this which adds some error messages for (c)transpose of AbstractMatrixs instead of removing the transpose methods defined for Any. For the record I'll note that I don't think it is the right solution as new matrix like types that are not subtypes of AbstractMatrix will silently return wrong results for (c)transpose.

For the QR example that revealed this issue, the result is now

julia> Q = qrfact(randn(3,3))[:Q];

julia> Q*diagm(randn(3))*Q'
ERROR: ctranspose not implemented for Base.LinAlg.QRCompactWYQ{Float64,Array{Float64,2}}. Consider adding parentheses, e.g. A*(B*C') instead of A*B*C' to avoid explicit calculation of the transposed matrix.
 in error at error.jl:21
 in ctranspose at abstractarray.jl:29

As part of the tranpose fix, I have added (c)transpose for Givens and Rotation types and changed the AbstractRotation to be an abstract type instead of a union. I have also removed the r property from the Givens type. Instead, it is returned from the givens method. The r property wouldn't make sense for the transposed rotation and I think it is a better design in general.

cc: @jiahao, @ivanslapnicar