Iterator test.
Merge branch 'master' of https://github.com/PDAL/PDAL into iter
More swap work.
Merge branch 'master' of https://github.com/PDAL/PDAL into iter
Working sort filter.
Merge branch 'master' of https://github.com/PDAL/PDAL into iter
Formatting.
Merge branch 'master' of https://github.com/PDAL/PDAL into iter

Conflicts:
	src/StageFactory.cpp
Fix bad merge.
Merge pull request #565 from PDAL/iter

Iter
Fix initialization order.
Use fewer threads for g++ to conserve memory.
Fix Windows linker errors (LNK2005, LNK2019)
add filters.attribute to stage list
Fix setting header system ID.
Merge pull request #566 from PDAL/windows-fixes

Fix Windows linker errors (LNK2005, LNK2019)
fix copy/paste bug in drivers.las.writer for CreationDOY/CreationYear