Provide a suite of pre-manufactured Kernels and kernel functions

[CKehl]

In discussion with Steffie and @dlobelle , and in line with #790 , it would be a good idea to cluster some common Kernel functionalities (e.g. aging, periodic [global] boundary conditions, particle deletions, etc.) into parcels or parcels_contributions, so to give new entry-level parcels practitioners a hand in starting there own simulations from a safe kernel baseline.

[CKehl]

see parcels_contributions for how-to submit essential scripts - from practitioners for practitioners