result to string converter support Iterable and Iterator.
PrintStream object for logging is changed to the instance variable of Runner from static variable.
update document.
Merge branch 'master' into 1.4-release

Conflicts:
	src/main/java/jp/vmi/selenium/selenese/Runner.java
	src/main/java/jp/vmi/selenium/selenese/TestCase.java
	src/main/java/jp/vmi/selenium/selenese/cmdproc/CustomCommandProcessor.java