Geo stream

[chrisuehlinger]

I just got legal approval for the Contributor Agreement, so here's my first contribution!

In reference to Issue #7, this PR contains the implementation of d3.geoStream, ported over from the v3.5.17 release of d3/d3.Tests have been ported to tape and relevant documentation has been brought over as well.

One thing to note: The first test in the stream suite was passing in v3.5.17 because the assert.fail() was throwing an error which was then caught by the try block. I rewrote that test in a way that I think preserves the intent, but it could probably use a second look.

[mbostock]

Well done! Two trivial things I noticed immediately:

• Please use two-space indentation.
• The d3_geo_ prefix is no longer needed now that we are using ES2015 modules. That was necessary with SMASH because SMASH simply concatenated everything into a shared namespace. It looks like a find-and-remove will work here. (Occasionally I rename things for clarity, but these names seem okay.)

[chrisuehlinger]

No problem!

I'll change my editor's settings to reflect the 2-space indentation.

[mbostock]

More trivial style nits:

• Don’t include the file extension (“.js”) in import statements.
• Don’t put a space between function and the open paren (().
• Don’t put a space after the opening brace ({) in an object literal.
• Don’t put a space before the closing brace (}) in an object literal.
• Do use a trailing newline at the end of every file.
• Use test.equal instead of test.isEqual.
• You don’t need to call test.pass.

Other things:

• The test “stream does not allow null input” should be called “stream ignores null input”, and catching the exception should be unnecessary since an uncaught exception will cause the test to fail naturally.

I’ll make these changes locally and then merge to save you the trouble.

[mbostock]

Actually, I’m just going to delete that test, since there’s already a test for null input geometries. That’s the bogus test you uncovered, anyway. 😁

[mbostock]

Thanks for the contribution!