Optional-imports

Fixed issue with some imports. If absolute and relative import fails like with:

python
import dask.array as da


a line running:

python
return importlib.import_module("..array", "dask.array")


is triggered.

Fixed issue with relative imports. Version 1.0.2 could not do `Client = optional_import("dask", "distributed.Client")`. This is now possible.

[1.0.1] - 2021-06-25 - Installation on-the-fly and Class inhertiance.

All goals seemed to be fulfilled in this version.

Added:
- OOP with class inhertiance
- Docstring for function
- Two more arguments (`user_install` prompts the user for install, `auto_install` automatically installs missing packages).

Changed:
- Docstring now part of `_optional_import` function.

Release. Class inheritance did not work in that version.
Using statements like `from package.subpackage.subpackage.subpackage._hidden import _hiddenClass` did not work.
This was because only the getattr() method was used, but some objetcs are not accessible that way.
That's what the from X.Y.Z import Class syntax was for.