Support for comments in CSV input.

[runejuhl]

I'm not sure if there's a basis for this functionality in PapaParse, but I stratched my own itch and you might as well benefit :)

It is configurable by setting config.commentChar to either a string, true (in which case it defaults to using "#") or false.

[runejuhl]

I thought I had tested well, but there seems to be a bug when header: false. I'll close it for now and have a look at it tomorrow. Sorry for the noise.

[mholt]

Looking forward to the revised PR!

[runejuhl]

So, had a look at it. I can't seem to figure out what was wrong yesterday, but it might've had something to do with Firebug 2.0/Firefox 30 breaking Sencha ExtJS. I'm unable to reproduce any errors with Firebug Scripts pane disabled in Firefox 31 and in stock Chromium 35.
If you have some more extensive tests, feel free to throw them at me, I'd be glad to run them.

[mholt]

First off, thanks for contributing!

It looks like the existing tests still pass, which is good, but when you have a chance, would you write test(s) to assert the behavior of the new comment feature? For instance, setting the comment character to the delimiter causes an infinite loop in the tests page. I know that's an edge case, but it's just another way to be defensive that we should consider.

As an aside, I just implemented this into version 3 of Papa Parse, complete with a whole new set of tests, including those for commented lines.

I'll be happy to merge this in with appropriate tests (that's just policy when changing the Parser).

[mholt]

I'm about ready to deploy version 3.0. As such, I'm going to merge this in so you get credit on the contributors page since you made the effort, and the feature persists in this next version. Thanks again!