VSIPLXX12 — Conformance statement

Please collect all conformance information from various locations in mars/12-03-09 into a single conformance statement in section 1.3 as discussed at the March 2012 AB meeting

The specification contains conformance criteria for (almost) each function
definition. It is therefore not feasible to move them all into a single section.
Instead, the existing conformance section has been amended with paragraphs
outlining these criteria generically, to help the reader find those conformance
points easily.
New items 1.3/1 and 1.3/2 (page 1):
1. Most functions in this specification are parametrized for the value-types
they operate on. The individual function specifications indicate which
value-types need to be supported in a compliant implementation.
2. Compliance criteria relating to the VSIPL++ Parallel specification are listed
in [dpp.oplevel]