Improved checks where substr_compare is used, replaced more substr + comapre cases with substr_compare

issue #746

Fixes #3358: Removed automatic CSRF meta tag generation by `View`. Added `Html::csrfMetaTags()` and its call to main layout files

added class references (current version without hyperlink)

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

fixes #2797

```
vendor/bin/indent --spaces -r framework/
vendor/bin/indent --tabs -r . --pattern=*.json
vendor/bin/indent --spaces -r . --pattern=*.md
vendor/bin/indent --spaces -r . --pattern=yii.*.js
vendor/bin/indent --spaces -r . --pattern=*.css
```

fixes #3551

fixes #3289

do not allow empty property name
fixes #3297

issue #3026

Fixes #2912: Relative view files will be looked for under the directory containing the view currently being rendered