*Not escape tags and double quots in tags,
 but find tags(icu regexp) when merge and
 use this infromation to make strings valid.
*Define a new Quot function for helpex,
 which works with icu UnicodeCharacter.
*Move tag search to xmlparse.cxx and use icu
 just in helpex.
*QuotHTML not unescape just replace xml charcters.
 (unescaping is also useless in uimerge.cxx)
*Move UnQuotHTML() to helper.
 (was used it in xmlparse.cxx and cfgmerge.cxx)
*Use UnQuotHTML() in uimerge.cxx too.

Change-Id: Ice8940ef69279709a1c5d84c6ae1b0d62a71ca76