Ability to pip install -e . so modules can be accessed the repo parent directory

[itsderek23]

If a user wants to write their own script that relies on DepthAI, they currently need to create it within the top-level of this repo. This is painful:

• Since this is checked out as a git repo, it's easy to mistakenly add the file to our repo and not your own repo.
• It's awkward to tell someone that they need to cd into their locally checked out copy

This PR adds a workaround so folks can access depthai and its dependencies globally.

The process on a local computer:

cd depthai-python-extras
pip3 install -e .

Then from anywhere on the host they can access depthai:

$ python3
>>> import depthai
>>> depthai
<module 'depthai' from '/home/pi/projects/depthai-python-extras/depthai.cpython-37m-arm-linux-gnueabihf.so'>
>>> import consts.resource_paths
>>> consts
<module 'consts' from '/home/pi/projects/depthai-python-extras/consts/__init__.py'>
>>> consts.resource_paths.device_cmd_fpath
'/home/pi/projects/depthai-python-extras/depthai.cmd'
>>> import sys
>>> sys.path
['', '/opt/intel/openvino/python/python3.7', '/opt/intel/openvino/python/python3', '/opt/intel/openvino/deployment_tools/model_optimizer', '/home/pi', '/usr/lib/python37.zip', '/usr/lib/python3.7', '/usr/lib/python3.7/lib-dynload', '/home/pi/.local/lib/python3.7/site-packages', '/home/pi/projects/depthai-python-extras', '/usr/local/lib/python3.7/dist-packages', '/usr/lib/python3/dist-packages']
>>> 

The e flag installs an editable python package that adds this repo's path to sys.path. Once it is added to the path, we're able to load modules.

You can see it via pip list:

pip list | grep depth
depthai-extras    0.0.0       /home/pi/projects/depthai-python-extras

This is an interim workaround to access depthai system-wide until we have a proper pip-distributed python package.

[itsderek23]

This is a more manual way to do it, but would require adding a line to top of every script or doing some unexpected-magic within our own files.

https://stackoverflow.com/questions/4383571/importing-files-from-different-folder

[itsderek23]

Tory verified this worked on his device.

[Luxonis-Brandon]

Fantastic! Thanks, both!