SYNOPSIS
	mapping m_delete(mapping map, mixed key)

DESCRIPTION
	Remove the entry with index 'key' from mapping 'map', and
	return the changed mapping. If the mapping does not have an
	entry with index 'key', the first argument is returned.

SEE ALSO
	mappingp(E), mkmapping(E), m_indices(E), m_values(E),
	m_sizeof(E)