Move tutorials

[atmyers]

Currently, the Tutorials directory contains a mix of things - tests of core functionality, specialized example programs, experiments that aren't actively used or tested, etc. We have decided to move the bulk of the Tutorials into a separate Github repo, keeping those that are really better described as "tests" in amrex.

This PR moves the subset of Tutorials that are tested regularly to Tests and removes the others from the main repo. The remainder can be found at https://github.com/AMReX-Codes/amrex-tutorials

The proposed changes:

• fix a bug or incorrect behavior in AMReX
• add new capabilities to AMReX
• changes answers in the test suite to more than roundoff level
• are likely to significantly affect the results of downstream AMReX users
• are described in the proposed changes to the AMReX documentation, if appropriate