add typed hcat/hvcat array literals

For example,

    Float32[1 2 3]
    Float32[1; 2; 3]
    Float32[1 2; 3 4]
touchups to 96d6ca40199df1a439c6b3f5f63bdd367ad07631
inline typed_hcat, typed_hvcat
Merge pull request #2481 from JuliaLang/mn/typedcat

add typed hcat/hvcat array literals