removed leading "_" in modules
further cleanup
fixed bug in group() with reverse=0 and integer axis
new union method, now check for sortedness of the axes when making a union
union of two monotonic axes (even singleton) is sorted
documentation improved for numpy along-axis transformation
new examples for `diff` method
- reshape now recognize comma notation `x1,x2` to group dimensions.
- better doc for `group`
reshape: does not transpose unless transpose=True if passed
fixed a bug in dropna, improved doc
made initialization a little stricter
new flatten method + improved doc
default axis name "unnamed" instead of "items" when passing through
Dataset. Get started looks final to me.