Commits
Wes McKinney authored 11c92bf282d
ARROW-1246: [Format] Draft Flatbuffer metadata description for Map Author: Wes McKinney <wes.mckinney@twosigma.com> Closes #876 from wesm/ARROW-1246 and squashes the following commits: 98790dfc [Wes McKinney] Review feedback to clarify nullability of map components 346b48dd [Wes McKinney] Typo 06ae8ebf [Wes McKinney] Draft Flatbuffer metadata for Map