v0.6.0

(breaking) groupby and groupreduce now select all but the grouped columns (as opposed to all columns) (#120)
(feature) usekey=true keyword argument to groupby will cause the grouping function to be called with two arguments: the grouping key, and the selected subset of records. (#120)
(breaking) leftjoin and outerjoin, operations don't speculatively create DataValueArray anymore. It will be created if there are some keys which do not have a corresponding match in the other table. (#121)
(feature) Not, Join, Between and Function selectors have been added.

v0.8.0

(breaking) Uses new redisigned version of OnlineStats
- (breaking) Does not wrap OnlineStats in Series wrapper. (#149) this means m = reduce(Mean(), t, select=:x) will return a Mean object rather than a Series(Mean()) object. Also value(m) == 0.45 for example, rather than value(m) == (0.45,)
(feature) - collect_columns function to collect an iterator of tuples to Columns object. (#135)
(bugfix) use collect_columns to implement map, groupreduce and groupjoin (#150) to not depend on type inference. Works in many more cases.
(feature) - view works with logical indexes now (#134)

(breaking) Switch from DataValues to Missing. Related: dropna has been changed to dropmissing.
(breaking) Depend on OnlineStatsBase rather than OnlineStats.

(breaking) Support for both DataValues and Missing (default). When join generates missing values, use the keyword argument missingtype to set the type (Missing or DataValue)
Use IndexedTables.convertmissing(tbl, T) to convert the missing values in tbl to be of type T.