show(io::IO)
More show fixes

We need to go through and explicitly type all function arguments
Clean up predicates; restore tests
Use Pkg.dir instead of julia_pkgdir()
Add stack_df for stacking using references (issue #145). New types:
StackedVector, RepeatedVector, and EachRepeatedVector.
Cleanups for stack_df, including a test case.
Fix dump for dataframes.
Add melt and melt_df (issue #29)
Fixed bug in merge()

Previously merge() never produced correct results for
 right or outer joins. This new implementation is a start
 to produce reliable results, but is probably only a 5%
 improvement
Updated to rand(1:N) instead of randi(N) style
Temporarily shut down tests broken by recent promote_type() changes.
Restore tests that depend on promote_type
Add pivot_table plus various other fixes related to reshaping (issue #29).
Merge in changes to add pivot_table (issue # 29).
Fix for Base searchsorted* name changes.
Minor doc fixes and comments on methods
Added read_rda to read saved R data sets.
Address deprecations