consistent print statements

We have the verbosity levels

from ..ion import htprint
htprint("Status", "No search radius provided; Assuming lattice spacing of the (p,q) tessellation!")
htprint("Warning", "The requested function is not implemented! Please use a different kernel!")

Furtheremore, errors should always be in this format

raise ValueError('[hypertiling] Error: Invalid value for argument "center"!')

@ythurn can you update the GR kernel family in this regard? Also feel free to add some more "status" statements if you like