MimeTypeController generates a map of file extensions to MIME types

It uses `mime.types` file from apache http located under
http://svn.apache.org/viewvc/httpd/httpd/trunk/docs/conf/mime.types?view=markup

This file has been placed in the public domain for unlimited
redistribution,
so we can use it and ship it with Yii.

see also yiisoft/yii#2851 and yiisoft/yii#2857

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.

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.