Grid reader

Sub-commands to support file reading. These are in technically components in that they render a full command line however they are not intended to be used directly but rather as sub-components of CGRID and INPGRID commands.

rompy.swan.subcomponents.readgrid.GRIDREGULAR	SWAN Regular Grid subcomponent.
rompy.swan.subcomponents.readgrid.READCOORD	SWAN coordinates reader.
rompy.swan.subcomponents.readgrid.READINP	SWAN input grid reader.