Al-adhan

Added custom exceptions especially for the following return codes:

- 400 Bad Request error: `BadRequestException`
- 429 Rate limited error: `RateLimitedException`
- 500 Internal Server error: `ServerErrorException`

They're avaialble in the `aladhan.exceptions`, could be directly imported from the `aladhan` module.

- New Wiki page: [Exception Handling](https://www.github.com/Kh4lidMD/AlAdhan/wiki/Exception-Handling)

_Started to save a copy of the Wiki pages in every release._

- Removed the `get_prayer_times` method, replaced with `get_today_times`, `get_calendar_times`, and `get_annual_times` methods.
- Fixed missing usage of `year` and `month` arguments in the calendar method.
- Added `callback` and `threaded_wait` arguments to the `Adhan.wait` method.
- Better code structure.
- These Wiki pages have been updated:
- [Get Prayer Times](https://www.github.com/Kh4lidMD/AlAdhan/wiki/Get-Prayer-Times)
- [Adhan Object](https://www.github.com/Kh4lidMD/AlAdhan/wiki/Adhan-Object)

- Changed `get_calendar` name to `get_prayer_times`.
- Added `today_only` parameter to `get_prayer_times`.
- Folder documentation removed.
- New better documentation hosted in the repository [Wiki](https://www.github.com/Kh4lidMD/AlAdhan/wiki).
- All `aladhan.location_types` objects are now available in the main import directly (e.g. `aladhan.location_types.City`_could_ be `aladhan.City`).
- Removed `ValueError` when only one of the year or month parameters is passed to `get_prayer_times`. Because the API does not return an error when one of them is missing.

- Added rakat method for the Adhan object, returns the number of rakat in salah.
- New Documentation

- Fixed import error (renamed `aladhan/location.py` to `aladhan/location_types.py`

- Changed PIP installation to `aladhan-api`