Make IlluminaTileMetrics inner class static and add another ctor so it can be used for writing TileMetricsOut in addition to reading.

git-svn-id: http://svn.code.sf.net/p/picard/code/trunk@1588 8bce386e-0d6e-43e0-b1ca-608082c0432d
Merge remote-tracking branch 'upstream'