846 - Removing unneeded plot arg in animator

Also typing return of animate to D3.Selection

Close #846.
Add in HorizontalLegend.

Lists entries side-by-side in the available width, after which the
entries wrap onto the next row. If an entry is too wide it is
truncated. If there are too many entries some rows will not be shown.

Close #755.
Remove comments on develop.
Streamline and clarify code.
846 - Removing unneeded plot arg in animator

Also typing return of animate to D3.Selection

Close #846.
Merge branch '846-removeAnimatorPlotArg' of github.com:palantir/plottable into 846-removeAnimatorPlotArg

Conflicts:
	plottable.js
Merge pull request #857 from palantir/846-removeAnimatorPlotArg

846 - Removing unneeded plot arg in animator
Refactors; add <title> for better readability.
Factor size calculations out into a separate call.
Missing semicolon );
Use D3.Map instead of Javascript Object

Renamed a few things as well.
Merge pull request #872 from palantir/755-horizontal-legend

Add in HorizontalLegend.
Release version 0.26.0
Merge pull request #888 from palantir/release-0.26.0

Release 0.26.0