Change how array type signatures are sprinted to match change in F# language

[stephen-swensen]

Per fsharp/fslang-suggestions#635 instead of e.g. int[] we should sprint int array where applicable.

The implementation is found in the ExtraReflections.fs file, given by the sprintSig function. Among other uses, this is used by the Type.FSharpName extension method.

@stephen-swensen May be similar case with list<_> and option<_>, should be _ list and _ option?

> typeof<float list>.FSharpName;;
val it : string = "list<float>"

> typeof<float option>.FSharpName;;
val it : string = "option<float>"

https://github.com/SwensenSoftware/unquote/blob/master/test/UnquoteTests/FSharpNameTests.fs#L12

@stephen-swensen jagged & multidimentional arrays, should also be changed to float array array ...?

> typeof<float array array>.FSharpName;;
val it : string = "float[][]"

> typeof<float[,,]>.FSharpName;;
val it : string = "float[,,]"