[jealousGH-130] CR window is not in the name. (jealous#131)

When user specify a customized window for the energy index, it
should appear in the column name. The customized column should not
overwrite the column with the default window size.

[jealousGH-122] Update calculation of `middle` (jealous#129)

The typical price or middle price is calculated by:
```
(high + low + close) / 3
```

But it would be accurate if the data source has the `amount` that
represents the total amount of capital traded in that period.
Use `middle = amount / volume` when amout is available.

Also fix some typos in the read me file.
Add some utilities for dropping columns, head or tail.

Add python 3.11 in CI and drop 3.9.

Update version to 0.5.0

[jealousGH-23] Add supertrend indicator. (jealous#111)

As title.  Also fix some issues in readme.

[jealousGH-108] Replace README.rst with README.md (jealous#109)

And update the readme to include more documentation.