Add xlimlabel function and help file, from Aimee
Fix bug in xlimlabel
Fix bug in example in help file for xlimlabel

  - Also, add par(mfrow=c(2,1))
Add some spaces in examples in help file for xlimlabel
Remove extraneous } from help file for xlimlabel

 - Also, link to text help file: it's in graphics, not base
NAMESPACE + version + Cosmetic changes to example in help file for xlimlabel