startable.readers property provides additional
input handlers which
can use for loading tables in named format mode.
Its value is a colon-separated list of class names, where each
element of the list must be the name of a class on the classpath
and has a no-arg constructor.
When a new
is constructed, an instance of each such named class is created and
added to its known handler list. Users of the library can therefore
read tables in the format that the new handler understands by giving
its format name when doing the load.