* lib_do_one_event() : change default value of the argument
 * lib_do_one_event() : returns true/false
 * add TclTkLib::EventFlag::NONE ( == 0 )
 * add set_no_event_wait() and get_no_event_wait()
 * modify MANUAL.euc and README.euc

tk.rb :
 * change default value of TkCore.do_one_event argument
 * add TkCore.set_no_event_wait(wait) and TkCore.get_no_event_wait
 * add Tk.exit ( == destroy root widget )

tkafter.rb :
 * rename TkAfter => TkTimer ( TkAfter is an alias name now. )
 * set_callback returns self
 * continue() raises an exception, if already running or no procedure.
 * skip() raises an exception, if not running.

sample/tktimer2.rb
 * new sample for TkTimer class.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@3965 b2dd03c8-39d4-4d8f-98ff-823fe69b080e