Have LineRenderer extend AreaRenderer

By default, AreaRenderer's stroke color is set to "none", and LineRenderer's
fill color is set to "none".

Close #501.
Close #506.
Remove RectRenderer
Reorganize the Plottable module structure as follows:

Plottable
  - Abstract
    *Axis
    * BarPlot
    * Broadcaster
    * Component
    * ComponentContainer
    * Interaction
    * Plot
    * PlottableObject
    * QuantitiveScale
    * Scale
    * XYPlot

  - Axis
    * Category
    * XAxis (to be deprecated)
    * YAxis (to be deprecated)
    * Axis  (to be deprecated)

  - Components
    * AxisLabel
    * Gridlines
    * Group
    * Legend
    * Table
    * TitleLabel
    * ToggleLegend

  * DataSource

  - Interactions
    * Click
    * Drag
    * DragBox
    * Key
    * Mousemove
    * PanZoom
    * XDragBox
    * XYDragBox

  - Plots
    * Area
    * Bar (rename to VerticalBar?)
    * Grid
    * HorizontalBar
    * Line
    * Scatter

  - Scales
    * Color
    * InterpolatedColor
    * Linear
    * Log
    * Ordinal
    * Time

  - Singletons
    * KeyEventListener
    * RenderController

  - Templates
    * StandardChart

  - Utils
    - Axis
    - DOM
    * IDCounter
    - Methods
    - OpenSource
    * ScaleDomainCoordinator
    * StrictEqualityAssociativeArray
    - Text
    - WordWrap
Fix build error
De-pluralize module names, and fix build
Fix compiler pointers
Fix Utils references
Merge in changes
Fixed merge in
Rename barPlot to VerticalBarPlot
Rename renderers to plots in filename
Rename folder and update reference
Make it all work
Rename Renderer -> Plot
update jsdoc
Merge branch 'master' into reorg-modules

Conflicts:
	plottable.js
Release version 0.15.0
Merge pull request #512 from palantir/reorg-modules

Reorg modules