Move EasyCore to EasyScienceCore permanently

[rozyczko]

Rather than have EasyScienceCore be a pypi name which contains EasyCore module, we ought to standardize on EasyScienceCore entirely.
The reason is clashes with another EasyCore package by another author.

The main issue is with the subsequent installations not working as expected:

1. user wants to work with (our) EasyCore
2. user runs pip install easycore without reading README.md, installing the wrong module
3. user realizes the module is incorrect and installs pip install easysciencecore
4. user tries to import easyCore <- this fails

The only solution at this point is to pip uninstall easysciencecore, pip uninstall easycore and pip install easysciencecore

The change woud impact everything: all the libs, apps and notebooks, including various school/course materials.

Alternate ideas are welcome.

[rozyczko]

Idea from @AndrewSazonov

Use EasyScience as main core project name, instead of EasyScienceCore.
This will allow easier specialisation of dependent modules inside, e.g. Fitting, Core, Utilities etc.

from easyscience.Fitting import fitter
from easyscience.Core import BaseObj
from easyscience.Utilities import ScicatConnector