Make terminal scrollback transparent by default

[o-sdn-o]

Changes

• Make terminal scrollback transparent by default to provide clear boundaries for the console applications output:

  <config>
  <term>
    <color>
      <bground = transparent />  <!-- Independent background color of the scrollback canvas. Set to 0x00ffffff(default) to sync with SGR49 (default background). -->
    </color>
  </term>
  </config>