termemu.js: don't warn on certain control sequences.

Don't print a debug message for some control sequences that technically
are unimplemented, but would just put the terminal into the only mode
yet implemented.  CSI 4l and CSI ?7h are like this.

termemu.js

@@ -1004,6 +1004,10 @@ var termemu = {
         if (params[i] == 1) {
           keyHexCodes.appCursor(true);
         }
+        else if (params[i] == 7) {
+          /* Wraparound ON is the only mode implemented. */
+          debug(0, "Wraparound mode");
+        }
         else if (params[i] == 1048) {
           this.saveCursor();
         }
@@ -1018,9 +1022,15 @@ var termemu = {
     else if (c == 108) {
       /* l - reset modes */
       if (prefix != '?') {
+        if (prefix === null && params[0] == 4) {
+          /* Insert mode is not implemented. */
+          debug(0, "Replace mode");
+        }
+        else {
           debug(1, "Unimplemented CSI sequence: " + comstr);
           return;
         }
+      }
       for (var i = 0; i < params.length; i++) {
         if (params[i] == 1) {
           keyHexCodes.appCursor(false);