newRPL: Comments revisited

[Claudio L.]

The topic of comments in the code was touched here before, but never put formally:
Comments will work this way (subject to opinions):

• A single @ will start a comment, which ends with another @ or a newline
• A double @@ will start a permanent comment, which ends with @@ or a newline
• A triple @@@ will start a multiline comment, which only ends with @@@ (so it can be used to comment out lines that include normal and permanent comments).
• Comments cannot be nested.
• When a comment ends in a newline, the newline gets stored as part of the comment, so it gets restored when the comment gets decompiled.