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.

Hotfix for #3597

Improved array support for "data" attribute in renderTagAttributes()

typo

Incomplete obsolete filling in i18n db extractor

Obsolete keys searching isn't work when we have serveral categories for tranlation with DbMessageSource. Obsolete array filled with last message category only, because it'll always overwritten.

Fix for #2020: docs about cross-DBMS relations

Fix #3429: Incorrect path to AppAssets at docs