Global pmm

[rogerfraser]

The changes in this pull request relate to a new feature that resolves issue icsm-au#53. Specifically, this includes:

• New reftran option to select whether to use the Australian plate motion model (default) or to determine which plate motion model parameters to apply according to station location, via --plate-model-option arg:
  0: Assume all stations are on the Australian plate (default)
1: Interpolate plate motion model parameters from a defined
set of global tectonic plates. For this option, a global
tectonic plate boundary file and corresponding Euler
plate motion parameters file must be provided.
• New reftran options to permit user entry of file locations for:
  • Global tectonic plate boundaries (via --plate-boundary-file arg), and
  • Euler pole parameters corresponding to the global tectonic plate boundaries (via --plate-pole-file).
• Creation of a reftran log file (<network-name>.rft). Depending on verbose level (via --verbose-level arg), output can include information about calculated transformation parameters from Euler pole parameters; sequence of steps involved in reference frame transformations; and reduced Helmert parameters and time duration.
• New files have been added to sampleData folder:
  • PB2002_plates.dig: List of plate boundaries defined by Peter Bird, 2003
  • PB2002_poles.dat: List of Euler pole parameters corresponding to the plates in PB2002_plates.dig.
  • TEST_ITRF05.SNX: Test SINEX file in ITRF2005.