checkstyle

Attached is a patch to pull out the common functions used by many of the
XSL report generation stylesheets, and make them be shared across all the
scripts.

Additionally, the patch fixes the checkstyle-author.xsl to group the error
results by author, to show error results for files with unknown authors,
and to list all authors, and not just those who need to apply fixes.
Attached is the result of running this updated report on the current (5.0
beta 3) checkstyle source. Note that there are some I18N errors and simple
spelling mistakes with peoples names in this output.

Also fixed one issue with the checkstyle-csv.xsl to wrap the value of the
error message attribute in quotes, but this needs extra work later to
escape any existing quotes in the message (CSV is harder than it looks).