ZOOM_connection_option_getl() now correctly sets its $len parameter.

Support for ZOOM_options_set_callback() -- *complicated*
Support for ZOOM_options_getl() and ZOOM_options_setl().
### Some memory-management issues remain.
Comment that ZOOM_record_get() should _sometimes_(!) use datachunk.
Testing complete for all other option-block functions:
	ZOOM_options_create_with_parent()
	ZOOM_options_create_with_parent2()
	ZOOM_options_get()
	ZOOM_options_set()
	ZOOM_options_destroy()
	ZOOM_options_get_bool()
	ZOOM_options_get_int()
	ZOOM_options_set_int()