Refactored two utility methods out of XMLParser into new class XMLParserUtils and added new range functionality to plates so that a plate range="1:10" will replicate the variable ten times with values 1, 2, ... , 10. The colon ":" range operator can be mixed and matched with comma-delimited (which take precedence) so that for example range="1,3:8,9" will replicate the variable eight times with values 1 and 3, 4, ... , 8 and 9.
Sampling using the classic root calibration
a text XML for the conditional calibration of the root.
Merge branch 'master' of https://github.com/CompEvol/beast2

Conflicts:
	src/beast/util/XMLParser.java
Merge branch 'master' of https://github.com/CompEvol/beast2
Resolves #223. JSONWriter is now used in the storeToFile method in Operator. A little hack was needed to handle NaN properly. I have also added quotes in the storeToFile() method in OperatorSchedule class.