w:ST_HpsMeasure is defined in ECMA-376 5th ed. Part 1, 17.18.42 as

  This simple type specifies that its contents contain either:
  * A positive whole number, whose contents consist of a measurement in
    half-points (equivalent to 1/144th of an inch), or
  * A positive decimal number immediately followed by a unit identifier.
  ...
  This simple type is a union of the following types:
  * The ST_PositiveUniversalMeasure simple type (§22.9.2.12).
  * The ST_UnsignedDecimalNumber simple type (§22.9.2.16).

This patch generalizes OOXMLUniversalMeasureValue to handle standard-
defined units, and introduces two typedefed specifications:
OOXMLTwipsMeasureValue (which is used where UniversalMeasure was
previously used), and new OOXMLHpsMeasureValue.

Unit test included.

Change-Id: Iccc6d46f717cb618381baf89dfd3e4bbb844b4af
Reviewed-on: https://gerrit.libreoffice.org/38562Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>