updated d3.d.ts, but broke everything

Incremental bugfixes we put into d3.d.ts are blown away.
I'm going to fix them, but I should have this checkpoint.
corrected a bunch of bugs in d3.d.ts

Now compiling. Will submit PR to DefinitelyTyped soon.
Merge pull request #729 from palantir/update-d3-definitions

Update d3 definitions
Release version 0.21.1
fix _getParsedStyle() and Label._requestedSpace
fixed lint bug, != instead of !==
Merge pull request #731 from palantir/slate-quickfix

fix _getParsedStyle() and Label._requestedSpace
Release version 0.21.2
Label.measureTextHeight() can never return 0
Merge pull request #733 from palantir/label-swap-0-for-1

Label.measureTextHeight() can never return 0
Merge branch 'master' into multi-time-axis

Conflicts:
	typings/d3/d3.d.ts