TST: Fix converter test for MPL1.4
Merge pull request #8054 from sinhrks/gh7233

TST: Fix tseries.converter test for MPL1.4
DOC: Fix Release note 8019, 8039
typo: "cubhelix" -> "cubehelix"
Merge pull request #8067 from ajschumacher/patch-1

typo: "cubhelix" -> "cubehelix"
Merge pull request #8068 from sinhrks/rn8019

DOC: Fix Release note 8019, 8039
PERF: StataReader is slow

StataReader does not make use of vectorized operations.

To improve performance, the following changes have been made:

* Use numpy.frombuffer to real the stored data in a single operation
* Vectorize date conversion
* Removal of unreachable private functions