ttyplot.c: Be robust towards input containing null bytes

> # { python3 -c 'print(chr(0))'; seq 20; } | ./ttyplot

ttyplot.c

@@ -519,6 +519,14 @@ int main(int argc, char *argv[]) {
             const ssize_t bytes_read_or_error = read(STDIN_FILENO, read_target, max_bytes_to_read);
 
             if (bytes_read_or_error > 0) {
+                // The data we read could contain null bytes, so we replace those
+                // by one of the supported delimiters to not lose all input coming after.
+                for (size_t i = input_len; i < input_len + bytes_read_or_error; i++) {
+                    if (input_buf[i] == '\0') {
+                        input_buf[i] = ' ';
+                    }
+                }
+
                 input_len += bytes_read_or_error;
 
                 // Last resort: truncate existing input if input line ever is