Support construction/conversion of UnitRange->SOneTo

[timholy]

Discovered in the context of

julia> a = SVector(SVector(1,2), SVector(3,4))
2-element SArray{Tuple{2},SArray{Tuple{2},Int64,1,2},1,2}:                                                                                                                                                                                                                     
 [1, 2]                                                                                                                                                                                                                                                                        
 [3, 4]                                                                                                                                                                                                                                                                                                                      
                                                                                                                                                                                                                                                                                                                             
julia> a'
1×2 LinearAlgebra.Adjoint{LinearAlgebra.Adjoint{Int64,SArray{Tuple{2},Int64,1,2}},SArray{Tuple{2},SArray{Tuple{2},Int64,1,2},1,2}}:                                                                                                                                                                                          
 [1 2]  [3 4]                                                                                                                                                                                                                                                                                                                
                                                                                                                                                                                                                                                                                                                             
julia> reinterpret(Int, a')
Error showing value of type Base.ReinterpretArray{Int64,2,LinearAlgebra.Adjoint{Int64,SArray{Tuple{2},Int64,1,2}},LinearAlgebra.Adjoint{LinearAlgebra.Adjoint{Int64,SArray{Tuple{2},Int64,1,2}},SArray{Tuple{2},SArray{Tuple{2},Int64,1,2},1,2}}}:                                                                           
ERROR: MethodError: no method matching SOneTo{1}(::UnitRange{Int64})                                                                                                                                                                                                                                                         
Closest candidates are:                                                                                                                                                                                                                                                                                                      
  SOneTo{1}() where n at /home/tim/.julia/packages/StaticArrays/3ENSR/src/SOneTo.jl:8                                                                                                                                                                                                                                        
Stacktrace:                                                                                                                                                                                                                                                                                                                  
 [1] convert(::Type{SOneTo{1}}, ::UnitRange{Int64}) at ./range.jl:123                                                                                                                                                                                                                                                        
 [2] oftype(::SOneTo{1}, ::UnitRange{Int64}) at ./essentials.jl:334                                                                                                                                                                                                                                                          
 [3] axes(::Base.ReinterpretArray{Int64,2,LinearAlgebra.Adjoint{Int64,SArray{Tuple{2},Int64,1,2}},LinearAlgebra.Adjoint{LinearAlgebra.Adjoint{Int64,SArray{Tuple{2},Int64,1,2}},SArray{Tuple{2},SArray{Tuple{2},Int64,1,2},1,2}}}) at ./reinterpretarray.jl:82                                                               
 [4] summary(::IOContext{REPL.Terminals.TTYTerminal}, ::Base.ReinterpretArray{Int64,2,LinearAlgebra.Adjoint{Int64,SArray{Tuple{2},Int64,1,2}},LinearAlgebra.Adjoint{LinearAlgebra.Adjoint{Int64,SArray{Tuple{2},Int64,1,2}},SArray{Tuple{2},SArray{Tuple{2},Int64,1,2},1,2}}}) at ./show.jl:1824                             
...

[coveralls]

Coverage increased (+0.03%) to 66.173% when pulling abc5564 on teh/soneto into d14604c on master.

[andyferris]

Nice one!

[andyferris]

As a side note unrelated to this PR (other than making me think of it) - I wonder if UnitRange([1,2,3])(or maybe convert(UnitRange, [1,2,3])) should work since the AbstractArray interface generally supports conversion between array types?