LUCENE-5364: Replace hard-coded Version.LUCENE_XY that doesn't have to be hard-coded (because of back-compat testing or version dependent behavior, or demo code that should exemplify pinning versions in user code), with Version.LUCENE_CURRENT in non-test code, or with LuceneTestCase.TEST_VERSION_CURRENT in test code; upgrade hard-coded Version.LUCENE_XY constants that should track the next release version to the next release version if they aren't already there, and put a token near them so that they can be found and upgraded when the next release version changes: ':Post-Release-Update-Version.LUCENE_XY:' (merge trunk r1549701)

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/branch_4x@1549703 13f79535-47bb-0310-9956-ffa450edef68