Add a blank line between the properties of the options object, in an
attempt at improving readability.

Initial approach at generalizing the function by extracting constants
from the options object of the scatter plot chart.

Add the basic structure of scatter plot chart

`Range selector` is analogous to the `zoom` of a chart. Set it to
display all the available observations from a datastream.

Get the max and min values of the heatmap color axis dynamically.
Fix the tooltip text for `null` observation values.

Deactivate datastreams that do not have observations

Formats datastream metadata for use in both linechart and heatmap

Add parameter for datastream metadata to function that draws line chart

Fetch datastream metadata together with the observations

Add parameter for datastream metadata to function that draws heatmap
chart

Fix typo in one of the property names. Perform minor tweaks to function.