Rename the files COPYING and COPYING.LIB to GPL and LGPL, respectively.

* While I am here, update the LGPL with the "Lesser" one.

* Move the "copying" sections of the files README and README.jp to
  COPYING and COPYING.jp, respectively.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@1586 b2dd03c8-39d4-4d8f-98ff-823fe69b080e