[UIMA-3936] improve clearing of annotations in html viewer to avoid many unneeded history entries

git-svn-id: https://svn.apache.org/repos/asf/uima/uimaj/trunk@1608143 13f79535-47bb-0310-9956-ffa450edef68
[UIMA-3934]

git-svn-id: https://svn.apache.org/repos/asf/uima/uimaj/trunk@1608144 13f79535-47bb-0310-9956-ffa450edef68