Rewrite to use unstructured grids

[amaggi]

Using rectangular grids for search regions involves doing a lot of calculations that are actually unnecessary. The code would be speeded up significantly if an un-ordered sequence of search points were used instead. This upgrade would also make it possible to craft a seismicity zone that more closely matches the observed pattern.

rt-waveloc development already uses such an unstructured grid.

[amaggi]

Mostly done.

Still need to deal with
[ ] plotting waveforms after location
[ ] plotting grid outputs for unstructured grids
[ ] test current example for resolution test
[ ] writing examples of synthetic and real tests with unstructured grids