Fix ambiguous ref definition
Merge pull request #215 from kmsquire/fix_ambiguous_def

Fix ambiguous ref definition
Temporary fix for #216
Also: really fix ambiguity warning.
Merge pull request #217 from kmsquire/temp_fix

Temporary fix for #216
Undo tempory fix due to infinite inference recursion.
Merge pull request #218 from kmsquire/undo_temp_fix

Undo tempory fix due to infinite inference recursion.
Fix ref{*} methods
Merge branch 'master' of github.com:HarlanH/DataFrames.jl into getset

Conflicts:
	src/dataarray.jl

Many other fixes: update for cor(), svd(), etc.