Code reorganisation and file naming

[pinpox]

After issue #8 I though this might be a point to bring up.

How would you go about the naming of the files and distributing the code in them? I suppose the "general" stuff that applies to any array type would go into numgo.go. For the Arrayb-specific methods we have bool.go. Where would you like the Array64-specific code?

It might be clearer to just have

• numgo.go: General stuff applying to any array type
• array64.go: A new file that holds Array64-specific code
• arrayb.go: bool.go renamed, containing Arrayb-specific code.

Just an idea, I'm open for any other suggestions

[Kunde21]

Sound good. We could use nDim.go instead of numgo.go so users don't expect anything special in the file named the same as the package.

This can be incorporated into #10 easily.