Azely

**Full Changelog**: https://github.com/astropenguin/azely/compare/v0.6.0...v0.7.0

This release closes the following issues.

- Use case-insensitive query 16
- For example, `query='query'` and `query='QuErY'` are considered to be same
- Other parameters are still case-sensitive (i.e., `frame='ICRS'` are not allowed)

- Rename cached TOML files
- `object.toml` → `objects.toml`
- `location.toml` → `locations.toml`

- Add feature to get user-defined information (7, 10)
- example: `azely.compute('user:GC', 'user:ASTE', ...)`
- Add feature to forcibly update cached information (4, 14)
- example: `azely.compute('Sun', '!here')`
- Add custom properties (`object`, `site`) to pandas DataFrame (11, 15)
- example: `df = azely.compute(...); print(df.site)`
- Rename property for LST axis (`as_lst` → `in_lst`)
- example: `azely.compute(...).in_lst.el.plot(ylim=(0, 90))`
- Add docstrings to modules, classes, and functions
- Add description and usages to README
- Add API docs made by sphinx

This release fixes internal code so that user can use Azely in Google Colaboratory.
If you install `python-dateutil >= 2.8.1`, then you will not encounter the bug.
No new features and no API updates in this release (same usage as v0.4.1).