Saxon extensions to the W3C XSLT/XQuery specifications

Added the EXSLT functions in package math: abs, acos, asin, atan, atan2, constant, cos, exp, log, power, random, sin, sqrt, tan. Thanks to Simon St. Laurent for these. Only partially tested.

The saxon:intersection and saxon:difference extension functions have been dropped; instead use either the XPath 2.0 operators (intersect, except) or the EXSLT functions.