PR: Split History module

[rlaverde]

• Move history to a module
• Also decouple the plugin UI in a widget to make it reusable and easy testable.

history/
├── confpage.py
├── __init__.py
├── plugin.py
├── tests
│   └── test_history.py
└── widgets.py

[goanpeca]

@rlaverde please fix docstrings. They should end in a period and use a single line if they fit. Always triple quotes

"""Something something something."""

or

"""
Something something something.

Extra something.
"""

[ccordoba12]

@rlaverde this PR doesn't contain any renames, so git won't be able to detect the right file when we want to merge changes from 3.x.

So I think you need to redo this PR and use renames instead.

[ccordoba12]

By renames, I mean git mv

[rlaverde]

There was only one file, I move it in 23a0615

but after that I move some parts of it:
to confpage: b904374 (as in other plugins modules)
to widgets: 59b3d19

because of that github doesn't detect the rename, and changes in the code moved to other files will have to be merged manually

[ccordoba12]

Ok, we need to be careful with changes to this plugin then.

[ccordoba12]

Parenthesis are not needed here.

[ccordoba12]

I left a minor comment, then I'll merge.