=begin RD

= ver.0.71
* subclass of PDF can be defined.
  (Thanks to Makoto Matsukawa and Nobuyoshi Nakada)
* PDF.open can be called with a block.
  In such a case, evaluate the block with an argument of
  an opend PDF file, and then close it.
* constants are defined under PDF::Constants module
  and PDF class includes PDF::Constants.

= ver.0.7
* support PDFlib ver.4 (but PDI is not supported)
* fix a bug in PDF#set_transition
  (Thanks to Fujikawa Norihide and WATANABE Hirofumi)
* add PDF#get_buffer (Thanks to Guillaume Pierronnet)
* PDF.new and PDF.open can be called without argument
  (for in-core PDF generation)

= ver.0.6
* support PDFlib ver.3.03 (Thanks to yuichi TAKAHASHI)
* clean up extconf.rb

= ver.0.51
* fix a bug in extconf.rb (Thanks to yuichi TAKAHASHI)
* add sample/jtext2pdf.rb (Thanks to yuichi TAKAHASHI)

= ver.0.5
* support PDFlib ver.3
* add image methods
* add sample/pdfimage.rb
* translate documents to RD format

= ver.0.4
* add link methods
* add sample/pdfgraph.rb
* add API documents (sorry, Japanese only)

= ver.0.3
* add color methods
* add sample/pdfclock.rb
* bug fix

= ver.0.2
* errors of PDFlib are treated as Ruby's exception
* add graphic methods

= ver.0.1
* text methods are ready
* sample/hello.rb and sample/text2pdf.rb work well

=end