Test / show CSV dialect / edge case support

[matt]

CSV has many edge cases / dialects that are treated differently by different parsers-- for example:

line1,"aaa
aaa",bbb
line2,aaa"aaa,bbb
line3,aaa",bbb

This can also significantly impact parsing speed (as well as correctness, depending on what the user would deem “correct”).

It would be useful to identify how each CSV parser handles edge cases; for simplicity, possibly one way to categorize would be “Excel” vs “non-Excel” dialect. Another might be to have a grid of all the different dialects, showing Y or N for each parser to whether that dialect is supported.