First step: make usage to textMeasure only take in text selections
643 - TextMeasurer takes in a temporary text node to measure against
Aligning usage to be in line with new getTextMeasure

Now measurers need only be created once and can be reused
Updating jsdoc on getTextMeasure
getTextMeasure -> getTextMeasurer
Minor format fix
792 - Forcing decimals to act correctly in percentage formatters

Close #792.
Merge branch 'master' into 643-improveTextMeasurer

Conflicts:
	plottable.js
	src/components/categoryAxis.ts
	src/components/numericAxis.ts
	src/components/timeAxis.ts
Merge pull request #818 from palantir/792-multipleOf7Percentage

792 - Forcing decimals to act correctly in percentage formatters
Merge branch 'master' into 643-improveTextMeasurer

Conflicts:
	plottable.d.ts
	plottable.js
Merge pull request #807 from palantir/643-improveTextMeasurer

643 - improve text measurer
Merge branch 'master' into 761-hover-interaction

Conflicts:
	plottable.d.ts
	plottable.js
Clarify some Doc, compact a function declaration.