use "IO" base class

like IO::File does, so that Chj::xIO (not merged here) can decide
whether the first argument is an IO handle or not, ok?
better concept

more symmetrical (and universal)
cleanup
add Browser_dryrun
add $separator
cleanup
create
cleanup
make usable for FP streaming, also accept separator as constructor arg
better error message

sigh, singlequote does not use escapes; should I change it?
add Ignore_CR feature
partial fixing and more cleanup
don't use (sigh)