Added methods to StringUtils and improved/fixed StringUtils.escHtml

Added:
- hexCharRef
- hasIsolatedSurrogates
- hasParagraphSeparators
- trim*
Added new helper methods in StringUtils, Utils and XmlGrammar
Added Utils.hasConstant
Added method to StringUtils which collapses multiple consecutive whitespace characters into a single space inside strings
Removed obsolete stuff
Moved basic visitor classes from Parser Toolkit to Utils
Added new PrinterBase class
Memoization can now be disabled and some stats are gathered
Little speed up for PrinterBase memoization
More detailed MultipleVisitMethodsMatchException
Added the "eatNewlinesOrIndents" concept to PrinterBase
Fixed TODO in StringUtils: Missing Exception handling
Added methods trimUnderscores, xmlDecode and urlDecode to StringUtils
Added missing license header
Extended PrinterBase, which is now also looking for newlines in Strings
Added Javadoc
Added MultiWriter class which replicates writes to a stream onto multiple other streams
Added *AtBol() methods to PrinterBase
Added method to generate a more or less safe filename from some arbitrary text
Fixed typo