Faster version of countna
Tests for countna
Merge pull request #670 from johansigfrids/fastcountna

Faster countna
Fix escaping of backslashes, make quote escaping play nice with allowescapes
Merge pull request #671 from JuliaStats/backslash

Fix escaping of backslashes, make quote escaping play nice with allowesc...
Remove unnecesary assigning of NA when construction empty DataFrame
Merge pull request #673 from johansigfrids/dontassignna

Don't unneecessarily assing NA when constructing empty DataFrames