Bscpylgtv

**Implemented enhancements:**

- Add new buttons
- Add `input_button` method

**Implemented enhancements:**

- Modify and remove unnecessary `turn_screen_*` methods

**Implemented enhancements:**

- Add optional `-o` command line parameter for getting hello info
- Add new buttons

**Fixed bugs:**

- Fix unhandled exception when QuickStart+ and TV is off (See [1](https://github.com/chros73/bscpylgtv/pull/1))

**Implemented enhancements:**

- Add optional `-v` command line parameter for displaying version number
- Remove unnecessary button methods
- Add new buttons

**Implemented enhancements:**

- Add optional `-s` command line parameter for setting static states and state updates
- Remove obsolete `-g` command line parameter
- Pass `self` into state update callback functions

**Fixed bugs:**

- Make subscribed state updates fail more gracefully when not supported
- Fix result of couple of state updates

**Implemented enhancements:**

- Refactor key db methods into external storage class
- Remove obsolete `-d` command line parameter
- Required Python version >= 3.8