Merge branch '0.50.0' into 'master'

.gitignore

.gitlab-ci.yml

Makefile

README.md

ci/appveyor/sakia.iss

ci/travis/debian/DEBIAN/control

gen_translations.py

requirements.txt

requirements_deploy.txt

requirements_dev.txt

res/i18n/ts/cs.ts

res/i18n/ts/de.ts

res/i18n/ts/es.ts

res/i18n/ts/fr.ts

res/i18n/ts/it.ts

res/i18n/ts/pl.ts

res/i18n/ts/pt.ts

res/i18n/ts/ru.ts

res/linux/usr/share/applications/sakia.desktop

src/sakia/__init__.py