INT E0 - REAL/32 - "N_ERRMODE" - SET NETWORK ERROR MODE

	CL = 48h
	DL = new error mode
	    FFh return error in registers AX,BX,CX
	    FEh display message and return error
	    FDh display message and abort (default)
Return: CX = error code (0000h successful, FFFFh failed)
	may destroy SI,DI???
Desc:	specify how the REAL/32 Net Server responds to error numbers 0CFFh,
	  0DFFh, and 0EFFh (see #04030)