Streamdeckfs

- New format for keys directories: `KEY_$ROW,$COL` instead of `KEY_ROW_$ROW_COL_$COL` (old format still supported)
- Variables and expressions work in whole names, not only in configuration part
- Add `SDFS_KEY_INDEX` and `SDFS_KEY_INDEX0` env vars
- Adding new keys sequences features

- Internal rework of references to handle variables

- Add `float` in expressions
- Fix special case of some filenames using `$VAR_SDFS_*` variables
- Add `SDFS_DEVICE_NB_KEYS` env var
- Handle variables to read from files that don't exist

- Decks access via browser
- Virtual decks

- Handle semicolon and slash replacements in texts
- Add the `enabled` configuration option, reverse of `disabled`

- Allow setting many vars in key events, independently from actions
- Set current directory to the deck/page/key triggering a command
- Add `quiet` configuration option for events
- Add floor divistion (via `||`, so we removed `concat`) and string conversion (via `str()`) to replace `concat` to expressions
- Add formating (via special `format()` function) to expressions
- Allow disabling emojis in texts