added new parameters for Table4.2-3-1,4-8,10-0,10-1,10-2, 10-4. (#106)

* added new parameters for Table4.2-3-1,4-8,10-0,10-1,10-2, 10-4.

* new parameters added to Table 4.2-0-2,4.2-0-3,4.2-0-4,4.2-0-5,4.2-0-6,4.2-0-19,4.2-0-20

* added new parameters to Table4.2-2-0,Table4.2-2-4

* updated params in TABLE 4.2-0-1 to reflect what was already put in the NCEP grib2 documentation website prior to updating g2tmpl

* fixed params to match grib2 documentation, added new parameters

* added new table: TABLE 4.2-0-21

* fixed duplicate entry DSWRFLX

* fixed potential evapotranspiration rate in 4.2-2-0