ER: give concat a better error message for incompatible types
Merge pull request #5011 from cpcloud/concat-err-msg

ER: give concat a better error message for incompatible types
DOC: prior version section in v0.13.0
BUG: Fix a bug when indexing np.nan via loc/iloc (GH5016)
ENH/CLN: Give AssertionErrors and nose.SkipTest raises a message
Merge pull request #5018 from jreback/column_nan

BUG: Fix a bug when indexing np.nan via loc/iloc (GH5016)
ER: give a better error message for hashing indices
Merge pull request #3730 from cpcloud/parse-exceptions

ENH/CLN: give all AssertionErrors and nose.SkipTest raises an informative message
Merge pull request #5019 from cpcloud/raise-on-index-hash

ER: give a better error message for hashing indices