fix(clipPath) Adding clipPath to prevent bleeding. (READY)

Bug Fixes
- This fixes the "bleeding" or overflowing of lines etc outside of the graph container.
- Also removed padding from the main graph container to fix weird double-border bug.

Layout Manager refactor:
- Removed JSHint override.
- Cleaned up loop and arg mutation.
- Commented out ridiculous test for now.
- Changed custom att name from `split` to `gl-split`.

d3.ext
- Refactored `.gl-layout-size` to be just `.gl-layout` since it's used for more than just size now.
- Added new clip() method that will add a clip path for any `<g>` element the same size as its `gl-layout` rect.

Layout Manger Feature:
- Will now optionally auto-apply a clip() if `clip: true` is provided in a container's layout config.