Fixed missing JavaDoc
Added isTrivial method and changed behavior of retrieving a value from
an empty TimeScaleFunction to returning 1.0.
Improved testing of isTrivial method
Changed XML tag.
Traffic demand now contains, reads and writes the TimeScaleFunction (if
it is non-trivial).
Multiplication works (and is tested)
Merge branch 'master' of https://github.com/OTSim/OTSim.git