added continuous mode support fix #3

If a command returns SHELLMATTA_CONTINUE all received data is passed to this command until it returns != SHELLMATTA_CONTINUE or a cancel is received
The data is passed stdin like and can be read byte by byte vie shellmatta_read
The stdin buffer is overwritten witch each new char

src/shellmatta_utils.c

@@ -366,6 +366,7 @@ void utils_terminateInput(shellmatta_instance_t *inst)
     inst->cursor            = 0u;
     inst->stdinIdx          = 0u;
     inst->stdinLength       = 0u;
+    inst->continuousCmd     = NULL;
     inst->write("\r\n", 2u);
     inst->write(inst->prompt, strlen(inst->prompt));
 }