These give the base URLs for MODIS downloads. Originally they were http://daac.ornl.gov
and http://daacmodis.ornl.gov; recently they
moved to https://daac.ornl.gov
and https://daacmodis.ornl.gov. These variables
will be initialized to values of getOption("MODIStools.daac", default = "https://daac.ornl.gov")
and getOption("MODIStools.daacmodis", default = "https://daacmodis.ornl.gov") in case there is
a future change.
