`FuncViewBuilder` to stack plots (#50)

This patch adds a `FuncViewBuilder` to consolidate multiple functional views
in a single plot.

Scatter view to render individual points (#49)

This patch defines a `ScatterView` to render individual points.

Add support of creating ticks with format style (#47)

This patch adds constructors for `HAxis` and `VAxis` to create respective
axes with a list of ticks and `FormatStyle`.

Add docs for LineView (#45)

This patch adds documentation (images) for line view.

Update README with doc links (#40)

This patch adds MIT license and updates README with useful links.