Update PooledDataVecs to handle IndexedVectors and PooledDataArrays.
More sorting methods.
Merge branch 'master' into indexingtweaks
More improvements on sorting, grouping, and indexed vectors.
Faster IndexedVector by using a better type signature.
Rearrange to get rid of warnings.
A few sorting tests. More sort/indexing tweaks.
Specific method for `ref` for DataArrays to improve speed (#186).
Tweaks to the specific method.
Add unique!/levels! for PooledDataArrays
Update README.md
Merge pull request #202 from catawbasam/patch-1

Update README.md
Updated methods for manipulating levels in PDAs (#203).
More PDV/levels tweaks.
Merge branch 'master' of git://github.com/HarlanH/DataFrames.jl
Renamed reorder! to reorder and levels! to set_levels, and changed
the PooledDataArray to not sort the pool if the pool is specified (#203).
Add set_levels! (#203).
permute!!() is not exported by Base
Merge pull request #204 from kmsquire/patch-1

permute!!() is not exported by Base
Add capability to merge on multiple columns (#17).
Merge branch 'master' of git://github.com/HarlanH/DataFrames.jl