This commit lets the user define the fields in the .wb that are going to
forwarded to the EPICS database.

if we have in the *.wb

~~~~~~~~~~~~{.wb}
      field {
         name = "Amplitude";
         ...
         epicsdb_egu  = "V";
         epicsdb_hopr = "1.5";
      };
~~~~~~~~~~~~

We will obtain in the *.db

~~~~~~~~~~~~{.wb}
record(ao, "$(user):AdcAmpSet")
{
	...
	field(DESC ,"Amplitude")
	field(EGU  ,"V")
	field(HOPR ,"1.5")
}
~~~~~~~~~~~~