Add Polish translation
Merge branch 'polish_translation' into 3.0 (PR #364)

This PR has been rebased before merging it. Closes #364
Fix some typos in the french translation
Added german translation
Merge branch 'german_translation' into 3.0 (PR #369)

This PR was squashed before merging. Closes #369
Merge pull request #375 from integrateurxhtm/patch-1

Fix some typos in the french translation
Portuguese translations
changed tem to contem
Changed `Snippets` to `Exemplos`