add delete column function do not fetch dataframe, closes #514
try removing combine lines
Merge pull request #531 from modilabs/delete-514

Delete 514
add exception for overlapping join cols
catch overlapping join cols exception, closes #529
add test for overlapping join cols
Merge pull request #532 from modilabs/overlap-err-529

Overlap err 529
update config doc file
add egypt demo image
update image
add image of election data
reset aggregation before parse
store calcs with dependencies
load external calculations with dependencies, closes #516
Merge pull request #533 from modilabs/calcs-516

Calcs 516
recursively encode queries, closes #534
refactor mongo reserved keys, closes #519
Merge pull request #535 from modilabs/or-534

Or 534
refactor update check, closes #521
more accurate column fetch