Improve Heatmap options' appearance
Improve Heatmap options' appearance

Moved the Heatmap display area above the table selection options (since
it didn't make sense to have it below those)

Added a button for clearing the Heatmap area and hiding the Heatmap
options

Added some margins to the Heatmap options

genenetwork/genenetwork2,genenetwork/genenetwork2,genenetwork/genenetwork2,genenetwork/genenetwork2