Draft for str tests.
Second draft of test involving n^2 addition of data dimension types to datashapes.
Fixed variable syntax error.
to_numpy_dtype ignores dimensions

This is useful if the dimension is var, and so would raise an error in
`to_numpy`
Merge pull request #93 from mrocklin/numpy-dtype-with-var

to_numpy_dtype ignores dimensions
option types on records when mixed with nulls
lowest_common_dshape recurses into Records
move record uniting from lowest_common_dshape to unite_base
speed up test_dshape_into_repr test
Merge branch 'tests'
remove toolz import
Merge pull request #94 from mrocklin/lowest-common-dshape-on-records

Datashape uniting within nested records