Class CMLayerGrid extends CM2Layer
  CMLayerGrid Class
 
  Displays a raster based on the numeric values in a JSON file.
 
  
  Copyright (C) 2020, Humboldt State University, Jim Graham 
  
  This program is free software: you can redistribute it and/or modify it under the terms of the GNU General 
  Public License as published by the Free Software  Foundation, either version 3 of the License, or (at your 
  option) any later  version. 
   
  This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the 
  implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 
  for more details. 
  
  You should have received a copy of the GNU General Public License along with this program. If not, see 
  .
Settings Group: Dataset
| Setting | Name | Type | Options | Default | Comments | 
| URL | URL | CMTYPE_STRING |  | null | Full or partial URL to the dataset to load into the layer | 
Object Functions
Object Functions 
RequestData(URL, DataSetType)
 Called to obtain the data for the layer from a URL.
 Depricated, use:
 - SetSetting("Dataset","URL",URL);
 - SetSetting("Dataset","Format",Format);
 - RequestData()
 TheView is required so the layer can be repainted when data is received. 
Parameters:
    URL - the URL to use to obtain data
    DataSetType - optional data set type (GeoJSON is the default)