comments from sf branch
comment changes from the sourceforge code base - so we can merge and use the sf version
relocate ITagNodeCondition and implementors to src/main/java/org/htmlcleaner/conditional

this will make merge with the sourceforge code.
more merge work
remove unneeded member variable in HtmlCleaner.

PrettyXmlSerializer: merge work - allow for indent string to be defined
merge work - htmlnode marker interface in sf code
squash!merge work
new property settings from sf code