Reverting changes and chosing edge splitting with random addition.

Extending new BC setup for rot_sub_init, editing the input file and
removing debugging output.

The transition zone is shifted so it lies above the indenter. This
ensures that, when using same numbers for h in BC definitions and in
surface parameters, the transition zone occurs in weaker overriding
plate.

x=1-face will be set to indenter velocities, if indenter is large
enough.
Strictflow will only set faces that don't cut the indenter.

Transition zone for BC only depends on distance from center.
define_bc_rot_sub_init.f90 still needs updating to the same setup.

New approach to the transition zone so that no conflicts at corners can occur.
Indenter peak can be freely chosen.

Allowing asymmetrical shapes, variable position of subduction and
reviving cylindrical option.

Age points are sent to external Python routine for interpolating onto
the current surface, read in again and a VTK surface file created.

Indenter can be rotated around the z-axis for angled influx.