Telegram-payment-bot

- Fix sentences sent during periodic payment check
- Fix some sentence names
- Exclude bots and self from username/payment check

- Payment check task is not statically configured anymore, but now it can be configured dynamically with specific commands
- Payment check on member join can be configured dynamically with specific commands
- Possibility to usa a "normal" log file handler in addition to the rotating file handler
- Add placeholders to translation sentences (in this way, they can be moved to different positions depending on the language)

- Add possibility to translate bot messages in different languages using a custom xml file (`app_lang_file`)
- Add possibility to leave some configuration fields empty (`support_email`, `support_telegram`, `payment_website`)
- Add possibility to check and change test mode without restarting the bot using commands `set_test_mode` and `is_test_mode`
- Add possibility to check payments data using command `check_payments_data`
- Add possibility to set the date format for payments data (`payment_date_format`)
- Add possibility to disable emails (`email_enabled`) and payment check when members join (`payment_check_on_join`)
- Payments data is checked for duplicated usernames and invalid dates
- Change periodical payment check period from seconds to minutes (`payment_check_period_sec` to `payment_check_period_min`)

First release