#417 Support dark theme in ESCET (console/legend/plotviz/checkstyle)

The first 4 dark theme changes for #417 (closed):

• Add application framework console dark theme support:

  • Different colors for light and dark theme.
  • Keeps same colors for light theme as used before.
  • Adapts to theme changes, even after application termination.

• Application status legend dialog improvements for dark theme:

  • 'Composite' with grid layout rather than a 'Tree'.
  • No more custom background color configuration.

• Added CIF simulator plot visualizer dark theme support:

  • Plot visualizer automatically applies light or dark theme.
  • Plot visualizer automatic theme switch upon Eclipse theme change.
  • Plot visualizer even changes theme after simulator has ended.
  • Light theme now implemented as a separate class.
    • Still based on the XChart's 'MatlabTheme'.
  • Added dark theme, extending light theme.

• ESCET development environment Checkstyle warning style change:

  • Current yellow background does not play well with dark theme.
    • On dark theme, blue/green text on yellow background is hard to read.
    • Does not affect ESCET product, nor affects end users.
  • Changed style to vertical bar rather than whole line becoming yellow.
    • New style is less obtrusive, and works well on light and dark theme.
    • Kept color the same.

I recommend reviewing per commit.

Addresses #417 (closed)