Fix sign of quadrupolar term and add test

Description

Fix quadrupole term sign, including other changes:

• Add input variable to allow the user to select the second-order coupling term (electric quadrupole, magnetic dipole or both)
• Fix condition bitand(TERM_OTHERS, terms_) /= 0 (issue #780 (closed))
• Fix test values
• Add test on total energy on regression test maxwell/12
• Add unit test to confirm that the quadrupole coupling is correct
• Solve refactoring issue #760 (closed)

Checklist

• I have checked that my code follows the Octopus coding standards
• I have added tests for all the new features added in this request.