.csv import: for large files, reading all in ram then decoding is not good..

[rcoreilly]

switch to interactive decode mode

also, still need to add the auto-detect of separator -- wrote that for something else very recently..

[rcoreilly]

and it is not parsing NaN properly, so those values end up as 0's.

[rcoreilly]

actually was parsing and setting Null flag, but not setting value to NaN, and graphing was not looking at Null flag..