ENH: added pick_channels Mixin as complement to drop_channels
ENH: added pick_channels Mixin as complement to drop_channels
ENH: added pick_channels Mixin as complement to drop_channels
ENH: added pick_channels Mixin as complement to drop_channels
ENH: added pick_channels Mixin as complement to drop_channels
Merge pull request #1217 from adykstra/add_pick_channels_mixin

ENH: added pick_channels Mixin as complement to drop_channels