Support the -insert (instead of overwrite kbrd mode) option in more UIFC apps

I think this is what nelgin/Keyop was asking for via IRC.

src/sbbs3/echocfg.c

@@ -650,6 +650,10 @@ int main(int argc, char **argv)
 	memset(&cfg,0,sizeof(cfg));
 	str[0]=0;
 	for(i=1;i<argc;i++) {
+		if(strcmp(argv[i], "-insert") == 0) {
+			uifc.insert_mode = TRUE;
+			continue;
+		}
 		if(argv[i][0]=='-')
 			switch(toupper(argv[i][1])) {
                 case 'D':

src/sbbs3/uedit/uedit.c

@@ -1940,6 +1940,10 @@ int main(int argc, char** argv)  {
 	uifc.esc_delay=500;
 
 	for(i=1;i<argc;i++) {
+		if(strcmp(argv[i], "-insert") == 0) {
+ 			uifc.insert_mode = TRUE;
+			continue;
+		}
         if(argv[i][0]=='-')
             switch(toupper(argv[i][1])) {
                 case 'C':

src/sbbs3/umonitor/umonitor.c

@@ -895,6 +895,10 @@ int main(int argc, char** argv)  {
 	boxch.bl=(char)200;
 	boxch.br=(char)188;
 	for(i=1;i<argc;i++) {
+		if(strcmp(argv[i], "-insert") == 0) {
+			uifc.insert_mode = TRUE;
+			continue;
+		}
 		if(argv[i][0]=='-')
 			switch(toupper(argv[i][1])) {
 				case 'C':

src/syncterm/syncterm.c

@@ -1489,6 +1489,10 @@ int main(int argc, char **argv)
 		text_mode=_ORIGMODE;
 
 	for(i=1;i<argc;i++) {
+		if(strcmp(argv[i], "-insert") == 0) {
+			uifc.insert_mode = TRUE;
+			continue;
+		}
         if(argv[i][0]=='-'
 #ifndef __unix__
             || argv[i][0]=='/'