Merge branch 'fftest' into develop: corrected termination criterion for series expansion, resulting in much higher accuracy (now all errors <5E-10)

continuity test requires revert of q_lim from 1e-4 to 1e-5; this requires relaxation of symmetry tests

merged qpa expansion code for prism and others; new termination criterion now also for prisms; works fine.

improved termination criterion for qpa expansion, improves worst-cast continuity by factor 2, and allows increase of qpa_limit