Pibooth

* Fix syntax error in the default configuration
* Update capture background image

* Add `HybridCamera` class to manage preview with `Picamera` and capture with `gPhoto2`
* Increase the time the led is ON when print button is pressed
* Add display of taken image in hybrid camera
* Rework the display of the foreground picture to work with `lanscape` pictures
* Add `[PICTURE][orientation]` option in the config
* Add German translations of background images
* Add 2 more LEDs for pibooth startup and preview
* Move size calculation in a dedicated module
* Handle capture with n photos != 4
* Remove option 'buffer' from the configuration
* Update default camera config to take the full advantage of the `Picamera` options
* Update camera handling to take a real picture with `gPhoto2` not only a preview
* Add option to flip the finale picture and manage option for multiple
* Manage resolution for `gPhoto2` preview and capture
* Update templates for a easier change between languages
* Show two different intro (with or without print)
* Rework the background images to add arrows
* Switch off the LED on quit
* Don't choose a layout by default
* Synchronize LEDs when they are blinking

* Add instruction to release `pibooth` in the Git repository
* Don't flip the preview when capture done by `gPhoto2`
* Add capture background, fix wording in choice background
* Avoid filling foreground buffer with `gPhoto2` preview
* Add `GpCamera` class for `gPhoto2` camera
* Update foreground image when window is resized
* Add an option in the config to start in fullscreen
* Add print delay in the configuration
* Double the timeout for the print screen
* Hide cursor when in fullscreen
* Use the `Picamera` overlay to display countdown
* Improve performances on resize/fullscreen using a buffer on background images
* Make `gPhoto2` and `CUPS` installation optional

* Add management of 1, 2, 3 or 4 pictures in merging functions
* Add workaround in README to disable install dependencies
* Use same button 'take picture' to choose layout
* Can select the number of captures
* Manage the states of the application using a State Machine
* Update countdown size according to window size
* Can choose different language (current are French and English)
* Use Amatic font in the application
* Show last taken picture in start image
* Add `Gimp` source files in the `templates` directory
* Add verbose/quiet option
* Add option in config to handle camera rotation
* Add `Lychee` gallery installation and configuration steps
* Add config key to select the printer to send pictures

Fix some issues and update keys in configuration