RFR: 206: Add proper escaping for replacement pattern

[Robin Westberg]

Hi all,

Please review this fix that adds proper escaping for replacement patterns in the `TextToMarkdown.escapeFormatting` function. Previously it was possible for exceptions to be thrown on certain input containing regex control characters.

Best regards,
Robin

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Commits:
 - 71ef4550: Add proper escaping for replacement pattern

Changes: https://git.openjdk.java.net/skara/pull/333/files
 Webrev: https://webrevs.openjdk.java.net/skara/333/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/SKARA-206
  Stats: 7 lines in 2 files changed: 5 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/skara/pull/333.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/333/head:pull/333

PR: https://git.openjdk.java.net/skara/pull/333