Add Soil Type

[leonard-psu]

To keep track whether a web user uploads a custom soil, modify soil etc, I added a "TYPE" attribute to Cycles soil file after CN. For example,

CURVE_NUMBER 75
TYPE 1
SLOPE 5
TOTAL_LAYERS 16

TYPE 1 -> the default gssurgo file
TYPE 2 -> means a soil file created via the GUI
TYPE 3 -> user uploaded soil file
TYPE 4 -> user modified gssurgo file
TYPE 5 -> modified gssurgo file (previously submitted)

Existing Cycles users can comment this line out, if they use the soil file generated by Cycles web services.

[leonard-psu]

Suggest code change to ReadSoil.c file is the following after
ReadKeyword(cmdstr, "CURVE_NUMBER", &Soil->Curve_Number, 'd', filename, lno);

NextLine(soil_file, cmdstr, &lno);
int soil_type;
ReadKeyword(cmdstr, "TYPE", &soil_type, 'i', filename, lno);

[shiyuning]

@leonard-psu If this is for the Cycles web services only, shall I create a branch for this in the development repository? That way the existing non-web users won't need to change their files.