Added an YAxisPlotLinesLabels class for consistency.

The class is empty as it has same content of XAxisPlotLinesLabels but
it allows to keep consistency with other similarly named classes in the code.
Added  X/YAxisPlotLinesLabel.Text property.

This property is missing from the reference docs, but it's present in
samples and it allows to actually set some text in labels.
Made use of the DashStyles ENUM instead of having the user use a string.
Added an additional sample for Highstock.

The additional sample is in Various Features/Plot lines on Y axis.
Added an YAxisPlotBandsLabels class for consistency.

The class is empty as it has same content of XAxisPlotBandsLabels but
it allows to keep consistency with other similarly named classes in the code.
Added an additional sample for Highstock.

The additional sample is in Various Features/Plot Bands on Y axis.
Fixed title.
Added an additional sample for Highstock.

The additional sample is in Chart Types/Line with markers and shadow.
Fixed wrong title.
Added an additional sample for Highstock.

The additional sample is in Chart Types/Spline.
Added an additional sample for Highstock.

The additional sample is in Chart Types/Step Line.
Added an additional sample for Highstock.

The additional sample is in Chart Types/Area.
Added an additional sample for Highstock.

The additional sample is in Chart Types/AreaRange.
Additionally highcharts-more.js was added in order to handle area Range.
Added missing file to handle AreaSpline.
Added an additional sample for Highstock.

The additional sample is in Chart Types/Area Spline Range.
Added an additional sample for Highstock.

The additional sample is in Chart Types/Column Range.
Added an additional sample for Highstock.

The additional sample is in Chart Types/Point Markers Only.
Added an additional sample for Highstock.

The additional sample is in Chart Types/Column.
Fixed name for OHLC.

The name was being serialized wrongly to oHLC,
now it will serialize correctly to ohlc.
Added an additional sample for Highstock.

The additional sample is in Chart Types/OHLC.