add test case capturing entity-unescaping issue described in ARI-3774
add more tests to FastArchivalUrlReplayParseEventHandlerTest (HTML entity escape/unescape)
fix AIR-3794: Wayback unescaping of url causes 404.
now WB re-escape rewritten URL before writing it out.
add/update javadoc based on investigation of ARI-3777.
cleanup code around ARI-3777
  remove unused imports/code lines
  replace deprecated import with new
add test capturing ARI-3777 - Transfer-Encoding: chunked header gets passed into response in proxy mode.
remove Transfer-Encoding header even in IdentityHttpHeaderProcessor. Fixes ARI-3777.
  consolidated common functionality of preserving original headers by prefixing into new base class - this changes behavior for corner cases of prefix being null or "" (now more consistent).
fixed ParseContextTest broken by commit 0d022943. document behavior change to ParseContext.resolve().
no material code change to ParseContext (just javadoc update and code formatting).
add unescapeAttributeValue property for disabling HTML-unescaping of attribute values. add test case for it.
CLEANUP code formatting.
Merge remote-tracking branch 'refs/remotes/kngnie/ARI-3777'
Merge branch 'ARI-3794'