[skip ci] Italian translation fixes

Fix Arabic translation

added class references (current version without hyperlink)

better usage of URL in latex

- better title page,
- book style,
- improved internal linking using labels and references

Route parameter url encoding added

Fix ErrorHandler

Update rest-quick-start.md: highlight automatic pluralization

bad grammar

This is probably not expected given the other naming conventions within Yii, so highlight this feature for beginners.