MacOS libraries

Hi, I wanna add MacOS support and I am using dylib you sent to Pierre. There is one issue with it..

I am not an expert in MacOS but I expect that there is smth like glibc and it should be backward compatible between OS versions. It means that to distribute compiled library and ensure that it works on different MacOS versions, library should be compiled on relatively old OS... BTW the same is true for Linux as well(thats why there is manylinux docker container)

Right now I am trying to load this library in macos 10.13(xcode 9.4 in travis CI https://docs.travis-ci.com/user/reference/osx/) and I see this:

INFO:root:b'  File "/usr/local/Cellar/python/3.7.5/Frameworks/Python.framework/Versions/3.7/lib/python3.7/ctypes/__init__.py", line 364, in __init__'
INFO:root:b'    self._handle = _dlopen(self._name, mode)'
INFO:root:b'OSError: dlopen(/usr/local/lib/python3.7/site-packages/brainflow/lib/libneurosdk-shared.dylib, 6): Symbol not found: _objc_alloc_init'
INFO:root:b'  Referenced from: /usr/local/lib/python3.7/site-packages/brainflow/lib/libneurosdk-shared.dylib (which was built for Mac OS X 10.15)'
INFO:root:b'  Expected in: /usr/lib/libobjc.A.dylib'

As for me it looks like you compiled this library in macos 10.15. It means that this library will never work on older OSes.

It will be good to rebuild it using older version if possible. First of all it will cover more OS versions and more users and it will allow to use travis CI with it. Looks like travis doesnt have 10.15 images at all https://docs.travis-ci.com/user/reference/osx/