Sharpened FilterLineItr tutorial, added ExceptionUtil

ADDED: com.github.xbn.lang.ExceptionUtil
ADDED: 1-string parameter constructor to GetBooleanFromString (defaults
true/false values to "true"/"false")
DOCS:
- IMPROVED: com.github.xbn.linefilter.FilteredLineIterator tutorial
(long import lists no longer displaying, input and full-source links for
all examples)