M_COAST Add a coastline to a given map.
M_COAST draw a coastline as either filled patches (slow) or
lines (fast) on a given projection. It uses a coastline database with
a resolution of about 1/4 degree.
M_COAST( (standard line option,...,...) ) or
M_COAST('line', (standard line option,...,...) ) draws the coastline
as a simple line.
M_COAST('patch' ( ,standard patch options,...,...) ) draws the
coastline as a number of patches.
See also M_PROJ, M_GRID