Redmine#3283: add a check for non-matching query
Redmine#3283: StringSetFromString handles NULL strings.  New StringSetToBuffer function.
Redmine#3283: Add tags string parameter to all the class and variable creating functions.
Redmine#3283: Fix search logic in variablesmatching and classesmatching.
Redmine#3283: add a check for non-matching classesmatching query
Redmine#3283: tag all classes and variables created by all agents
Redmine#3283: fix classesmatching and make StringSetToBuffer take a single char
Redmine#3283: constify tags, fix tests, VariableNew takes a tags StringSet
Redmine#3283: find more places to tag through the magic of "git grep"
Merge pull request #1094 from tzz/feature/redmine3283-tag-everything-n-stuff

Redmine#3283: tag everything