reform comments.
add Filter Parser facility on SAX2 parser.
add checking facility of attribute in filter.
add several class-access utility for Quebec City.
Implement SAX2 facility in ItkXml.  Reform gnuplot.rb for rdocs.
Introduce error bar facility in gnuplot.rb
add history comments
Reform StatInfo.rb.
specify line style for normal plot, to let styles of error bar the same.
add PoissonProcess.
add Exponential Moving Average.
add DirectConfAttrList facility to set direct value assignment by conf.
gnuplot のエラーメッセージを表示できるように改変。
Change module of Numeric#value method to the built-in one.
add ExpLogger as a lib