Integrate the ncdmr.cc code into the netCDF handler so that it is used for the DMR response.

Issues TODO:

https://docs.opendap.org/index.php/DAP4:_Specification_Volume_1#DMR_XML_Format

1. DMR template or xml schema:
   Grid, map ... etc.

2. Path for attributes in case of compound type (groups).

3. Dot or underscore in names. (For instance name="_4.4_KM_PRODUCTS_X_Dim").

4. Should avoid the same dimension in different groups?