Root-pandas

Fix recursive brace expansion 65 (thanks tmadlener!)

Features:
- Add support for `noexpand:` prefix to allow formulas in column names 14

Bugfixes:
- Exclude columns that are not one-dimensional 19
- DataFrame chunks will have duplicate indices 24
- Require pandas >= 0.18.0 34

Contains 2 bug fixes:
- Fixed use of `filter` on Python 3
- Fixed a call to `map` when ignoring columns