Allow creation of new validators on the fly

This is useful for extensions and/or behaviors.
I could do it outside the model, but I think it belongs in it.
Update changelog
now return $this allowing method chaining

also added @since tag
fixed log order
Adjusted tests for CHtml::refresh() regarding to fix for issue #2239
new line after method

just to keep the standard
doc fix
Added "Symlinking assets" section to Guide's "Performance Tuning"
[NL] Update for latest code revision
Merge pull request #2262 from Blizzke/master

[NL] Updated
Added link to wikipedia article about what symlink is
Merge pull request #2260 from samdark/add-symlinking-assets-to-performange-guide

Added "Symlinking assets" section to Guide's "Performance Tuning"
Enh #1447: CSqliteSchema: added enabling/disabling integrity check for sqlite. PR #1449.
Failing test fix.
Fixes #2258. CJuiSliderInput didn't support string typed 'range' option.
Kazakh (kk_KZ) messages updated.
Russian (ru_RU) messages updated.
Merge pull request #2132 branch '2131-add-accept-header-parsing' of https://github.com/Rupert-RR/yii into Rupert-RR-2131-add-accept-header-parsing

* '2131-add-accept-header-parsing' of https://github.com/Rupert-RR/yii:
  Yii code style correction
  Removed unnecessary spaces.
  Transferred data for unit tests from the test functions into data providers.
  Undo accidental permissions change on bootstrap.php
  Added unit test file for CHttpRequest for the methods parseAcceptHeader() and compareAcceptTypes(). Modified the regexp in parseAcceptHeader() to accept wildcards in the path. Modified the description of compareAcceptTypes() to better reflect the comparison result (higher preference returns lower value, so that most preferred is first in the array).
  parseAcceptHeader() function description tidy up.
  Typo corrections and code tidy up.
  Altered parseAcceptHeader() to use only one regexp. Thanks to Ka on StackExchange for this expression.
  Typo corrections
  Separated out parse and compare functions. Reduced regular expression count to 2 from 3. Modified MIME type array map structure.
  Added #135 back in changelog, which got lost somehow..
  Moved position of line to follow numerical order.
  Enh #2131: Added Accept header parsing to CHttpRequest to give an array of accepted types in order of preference

Conflicts:
	CHANGELOG
php doc adjustments after #2132
Merge branch 'Rupert-RR-2131-add-accept-header-parsing'

* Rupert-RR-2131-add-accept-header-parsing:
  php doc adjustments after #2132
  Yii code style correction
  Removed unnecessary spaces.
  Transferred data for unit tests from the test functions into data providers.
  Undo accidental permissions change on bootstrap.php
  Added unit test file for CHttpRequest for the methods parseAcceptHeader() and compareAcceptTypes(). Modified the regexp in parseAcceptHeader() to accept wildcards in the path. Modified the description of compareAcceptTypes() to better reflect the comparison result (higher preference returns lower value, so that most preferred is first in the array).
  parseAcceptHeader() function description tidy up.
  Typo corrections and code tidy up.
  Altered parseAcceptHeader() to use only one regexp. Thanks to Ka on StackExchange for this expression.
  Typo corrections
  Separated out parse and compare functions. Reduced regular expression count to 2 from 3. Modified MIME type array map structure.
  Added #135 back in changelog, which got lost somehow..
  Moved position of line to follow numerical order.
  Enh #2131: Added Accept header parsing to CHttpRequest to give an array of accepted types in order of preference