Things to do:
=============
-- String: Boundary checking on index and subtring operators
-- String: test cases for numerical conversion
-- String: Implement String != regex operator
-- String: index and rindex methods with String argument
+- String: format operator % like in python
+- String: assign fstream objects to read and write a file
+- String: convert to and from std::sstream
+
+- SuperString: sort and uniq
+- SuperString: find (regex)
+- SuperString: remove empty elements or elements macthing a pattern
- date: test parser for invalid dates and syntax errors
- date: Parser for stream input
-- date: Weekday and week number
+- date: Yearday, Weekday and week number
+
+- UTC: Convert to and from struct tm
-- UTC: Convert to and from time_t, struct tm
+- xml: Xinclude processing
-- Add classes: configuration, Integer, amount
+- configuraion: Handle environment variables to override parameters