add mult-select column type
add num columns
rename to SplitColumn
split column test cases
settings cleanup
update SplitColumn for format 2
add allOptions to column config dict
allow column display to contain format param
Merge branch 'master' into multi-select-export
add doc string for SplitColumn
change default header format
make unmatched columns blank
make tests with without custom doc
fix tests after change to header format and empty value
Merge pull request #108 from dimagi/multi-select-export

Add support for split columns