ENH: extend selection semantics on ordered timeseries to unordered
closes #2437
closes #2787
closes #3070

related #3070  
Selection semantics should be a property of the underlying index type, not the data 
container type wrapping it.
 thanks....pretty straightforward to wrap up #3070 in this

going for a 3-fer
 do it in seperate branches and use an octopus merge ftw.
 what's an octopus merge?
 [this](https://secure.flickr.com/photos/sermoa/3425577867/)
 moved to other PR's
