Update heat map

[Keboo]

Here is a matrix of what the heat map should look like:
1.0 is good, 0.0 is bad. This should be represented as a linear gradient.

Sample heat map (this is much smaller, and should be scaled out to match the source stream size)

[
  [0.1, 0.5, 0.1, 1.0, 1.0, 1.0, 1.0, 0.5, 0.1]
  [0.2, 0.7, 1.0, 1.0, 1.0, 1.0, 1.0, 0.7, 0.2]
  [0.2, 0.7, 1.0, 1.0, 1.0, 1.0, 1.0, 0.7, 0.2]

  [0.1, 0.6, 1.0, 1.0, 1.0, 1.0, 1.0, 0.6, 0.1]
  [0.1, 0.5, 0.8, 0.8, 0.8, 0.8, 0.8, 0.5, 0.1]
  [0.1, 0.2, 0.5, 0.5, 0.5, 0.5, 0.5, 0.2, 0.1]

  [0.0, 0.1, 0.2, 0.2, 0.2, 0.2, 0.2, 0.1, 0.0]
  [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
  [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
]

When the heatmap is selected draw the overlay with 50% opacity.