Make attr setters in Plottable chainable
Move @chainable to decorators, don't give the honor to stupid Set-ters.
Merge pull request #207 from ekfriis/chainable

Make attr setters in Plottable chainable
When converting an Efficiency to a Graph, rootpy-ize it.
Optionally allow the legend label to be specified directly.
Make sure equivalent graph has the same style options
Fix bug where kwargs were not expanded
Merge pull request #208 from ekfriis/master

Minor usability improvements
log the filter status: active or in pass-through mode
log a warning if a filter returns None