Fixed FileSchemeFunction to work with both absolute and relative file
paths
Fleshed out the WindowInformation class to use proper getters and
setters, including the concept that you cannot change the duration
without specifying the time units, but you can change the time units
such that it automatically side-effects to the value held for the
uration, to keep the actual duration the same (to the accuracy of the
new granularity).
updated the TestJenaRuleCompilerFunctions test to use the proper
FixedJoinFunction constructor.