allow table to be copied in table syntax

[shriram]

Right now, copying a table produces a TSV. This is very useful.

But there are times when it's also useful to copy into Pyret syntax (table …). You might have imported a large table from Google Sheets, and either want to paste it directly into source (to avoid autograder problems) or want to make it smaller and illustrative to include in your code.

In these cases, it's a real hassle to reconstruct the entire thing in Pyret syntax. Whereas Pyret knows how to generate this in its syntax.