RFR: 8233226: Implement XOR Mode rendering option

[Ajit Ghaisas]

Issue : https://bugs.openjdk.java.net/browse/JDK-8233226

-------------

Commit messages:
 - XOR mode for primitives and text

Changes: https://git.openjdk.java.net/lanai/pull/72/files
 Webrev: https://webrevs.openjdk.java.net/lanai/72/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8233226
  Stats: 327 lines in 8 files changed: 283 ins; 24 del; 20 mod
  Patch: https://git.openjdk.java.net/lanai/pull/72.diff
  Fetch: git fetch https://git.openjdk.java.net/lanai pull/72/head:pull/72

PR: https://git.openjdk.java.net/lanai/pull/72