Get ELSE IF working?

[dansanderson]

We have IF ... ELSE ... THEN, and we can make their statements into blocks with BEGIN ... BEND. However, for some reason ELSE comes with syntax restrictions that prevents ELSE IF from working properly. We should look into this.

10 X=1
20 IF X=0 THEN BEGIN
30   PRINT "ZERO"
40 BEND:ELSE IF X=1 THEN BEGIN
50   PRINT "ONE"
60 BEND:ELSE IF X=2 THEN BEGIN
70   PRINT "TWO"
80 BEND

This prints "ONE" and "TWO". It should only print "ONE".

The documentation for ELSE implies a bunch of odd syntax restrictions. If this is an inherent limitation, we should try to understand and document it better.

[dansanderson]

Previous discussion: https://www.forum64.de/index.php?thread/111002-mega65-rom-benchmark-results/&postID=1622976#post1622976

[dansanderson]

Notably, it is expected behavior for BEND to demarcate a line, not a statement position. The rest of the line is ignored. It's counterintuitive but it has existed since BASIC 7.

Also notably, putting the ELSE IF clauses on separate lines from the BENDs doesn't fix the issue.