Allow concatenation of empty GTuples.
Check for NA in tuples
Don't allow NAs in tuples
GTuples validity improvements when size = 2.
Code tidying
Fix bug in granges,GTuples-method
Use update() in GTuples,tuples<-
Cody tidying
Allow GTuplesList of empty GTuples.
Update to examples in GTuples and GTupleList docs
Add unittest infrastructure (using testthat package)
Began writing tests of GTuples-class.R