enhance(ink) - perf improvements & refactor $ripple simplify implementation

rippler.js - Remove orphan variables and improve code clarity; now uses `new $ripple( ... )`
tabs.js - method renames for clarity
throttle.js - updates for API changes in $ripple
docs(layout): layout lines only for demos
feat(keylines): standard vertical heights
fix(docs): use flexbox for scrollable areas
fix(docs): use momentum scrolling
feat(padding-base): padding from baseline grid
fix(ink) - updated perf improvements and component usages

rippler.js
- Remove orphan variables and improve code clarity; now uses `new $ripple( ... )`
- fix cleanup of waves at max radius and opacity drawings of waves
- restore use of mixin() function
throttle.js - updates for API changes in $ripple
tabs.js - method renames for clarity
_tabs.sccs - updated `material-tab` style to **not** allow tab button content text selection
radio-button.js
- changed css of ripple to always be green; since radio buttons toggle different from checkboxes
- fixed ripple z-index to render **below** the box
check-box.js
- fixed ripple z-index to render **below** the box
fix(ripple) - default values of ripple now used for non-tab components