Bcolz

- C-Blosc internal sources updated to 1.14.3. This basically means that
internal Zstd sources are bumped to 1.3.4, which may lead to noticeable
improved speeds (specially for low compression ratios).

- `np.datetime64` and other scalar objects that have `__getitem__()` are now
supported in `_eval_blocks()`. PR 377. Thanks to apalepu23.

- Vendored cpuinfo.py updated to 4.0.0 (ARM aarch64 is recognized now).

- Allow setup.py to work even if not on Intel or ARM or PPC archs are found.

* Support for Python <= 2.6 or Python <= 3.4 has been deprecated.

* C-Blosc internal sources updated to 1.14.2. Using a C-Blosc library > 1.14 is important for forward compatibility. For more info see: http://blosc.org/posts/new-forward-compat-policy/

- Allow to delete all the columns in a ctable. Fixes 306.
- Double-check the value of a column that is being overwritten. Fixes
307.
- Use `pkg_resources.parse_version()` to test for version of packages.
Fixes 322.
- Now all the columns in a ctable are enforced to be a carray instance
in order to simplify the internal logic for handling columns.
- Now, the cparams are preserved during column replacement, e.g.:

`ct['f0'] = x + 1`

will continue to use the same cparams than the original column.
- C-Blosc updated to 1.11.2.
- Added a new `defaults_ctx` context so that users can select defaults
easily without changing global behaviour. For example::

with bcolz.defaults_ctx(vm="python", cparams=bcolz.cparams(clevel=0)):
cout = bcolz.eval("(x + 1) < 0")
- Fixed a crash occurring in `ctable.todataframe()` when both `columns`
and `orient='columns'` were specified. PR 311. Thanks to Peter
Quackenbush.