Fix issue with very large text.

Text larger than 2048×2048px was overflowing the internal buffer,
causing it to incorrectly appear in the layout.

Fixes #16.
Version 1.0.2.
Fix #18: variable padding.
Remove debug line.
Update copyright year.
Remove outdated test.

Fixes #24.
Remove require from main layout file.

This also includes a backwards-incompatible change to module naming when
used with Node.js: instead of require("d3-cloud").cloud, you should now
use require("d3-cloud") directly.

Fixes #28.
Bring fork up to date with original master
Merge remote-tracking branch 'jasondavies/master' into combined