diff colors for themes

diff.xml

<dict>
  <key>name</key>
  <string>diff.header</string>
  <key>scope</key>
  <string>meta.diff.header</string>
  <key>settings</key>
  <dict>
      <key>foreground</key>
      <string>#ffffff</string>
      <key>background</key>
      <string>#77aadd</string>
  </dict>
</dict>
<dict>
  <key>name</key>
  <string>diff.deleted</string>
  <key>scope</key>
  <string>markup.deleted</string>
  <key>settings</key>
  <dict>
      <key>foreground</key>
      <string>#F55</string>
  </dict>
</dict>
<dict>
  <key>name</key>
  <string>diff.inserted</string>
  <key>scope</key>
  <string>markup.inserted</string>
  <key>settings</key>
  <dict>
      <key>foreground</key>
      <string>#9F9</string>
  </dict>
</dict>
<dict>
  <key>name</key>
  <string>diff.changed</string>
  <key>scope</key>
  <string>markup.changed</string>
  <key>settings</key>
  <dict>
      <key>foreground</key>
      <string>#F55</string>
  </dict>
</dict>