Fix bug whereby L & Y would not find a string at the end of a max-length line;
Suppress "Long line found" warning for a line that is exactly max length;
Word macro ^N^A now tolerates a word which is longer than requested line length;
New ALU opcode DUP pushes a copy of R;
New "tests" directory in source tree has long line yetch cases;
This is Q version 21.