Don't read the header twice when using a WFIterator (in outer class constructor and then again in WFIterator); instead, skip the header when generating the PBS for the WFIterator.

git-svn-id: http://svn.code.sf.net/p/picard/code/trunk@1527 8bce386e-0d6e-43e0-b1ca-608082c0432d
Simplify documentation, and modify to make consistent with method-level documentation.

git-svn-id: http://svn.code.sf.net/p/picard/code/trunk@1528 8bce386e-0d6e-43e0-b1ca-608082c0432d
Merge remote-tracking branch 'upstream'