Port to the new AtomSpace API

[linas]

The new AtomSpace uses smart pointers for memory management (just like Atoms. You can even store it in a Handle !) This means several things:

• Cannot allocate AtomSpaces on stack; they must be in the heap.
• Cannot put AtomSpaces into structs; only AtomSpacePtr
• Must use createAtomSpace() instead of new AtomSpace()

So these are "minor" changes, but they do need to be made. Merge whenever it is convenient: the old asmoses won't work with the new AtomSpace, and v.v.

[linas]

I'm going to merge this, because without it, the circleci unit tests break.

[ngeiswei]

Thanks @linas (I had meant to look into it but I didn't have time).