Squashed 'external/trappy/' changes from 84472d8d..a8abc5d8

a8abc5d8 Merge pull request #290 from derkling/optimize-df-memory
9b3dc0c6 trace/base: Optimizing DataFrame memory footprint
79ff2382 Merge pull request #292 from qais-yousef/handle_duplicate_indices_in_dframe
d6046934 grammer.py: remove unnecessary call to handle_duplicate_index()
9a9ca2c5 base.py: handle any duplicated indices when creating dataframe
515a5270 utils.py: take __line into account in handle_duplicate_index()

git-subtree-dir: external/trappy
git-subtree-split: a8abc5d8b55e3407c5b52f2b3d77ec3e62d69a7c