Update the schematron rules when small arrays of dataType attributes are allowed

[pahjbo]

the schematron error that is currently issued when an attribute which is a dataType has multiplicity > 1 should only be issued when the multiplicity is > n (where n is yet to be decided) to conform with

Section 4.19, page 50 of the VO-DML standard states:
A special case is the assignment of a Multiplicity to an Attribute. Users are
strongly encouraged to only use the following combinations of
minOccurs..maxOccurs: 0..1,1..1 (or simply 1), and 0..n, or n..n with n an
explicit integer value >1. For multiplicity greater than 1 the attribute must be
interpreted as an array of fixed size. To indicate that the value of such an array
attribute is optional, the multiplicity 0..n must be used (i.e. minOccurs=0,
maxOccurs=n). For maxOccurs n > 1, minOccurs can only be 0 or n, other
values are meaningless and illegal.