LUCENE-5952: better error messages when version fails to parse; use simpler string tokenizer; don't check major versions at such a low level

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/branch_5x@1626546 13f79535-47bb-0310-9956-ffa450edef68
LUCENE-5952: remove dead writer.version parsing code

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/branch_5x@1626552 13f79535-47bb-0310-9956-ffa450edef68