[#4761] Convert exceptions to warnings

- To retain BC, filters should never raise exceptions
- Instead, raising warning and returning original value
[#4761] Added tests for null values

- null values should be filtered without warnings
[#4761] null values should not raise warnings

- null values should not be filtered, and should not raise warnings
[#4766] wrote tests to indicate behavior is opt-in

- Added `setUseIncludePath()` call to translator adapters
- added flag, Factory::USE_INCLUDE_PATH, as second argument to config
  factory
[#4766] Config makes include_path usage opt-in only

- You must pass the `$useIncludePath` to either `fromFile()` or
  `fromFiles()` for it to be used. Constants were created with boolean
  values for those using IDEs.
[#4766] Make include_path abilities opt-in in Translators

- Created AbstractFileLoader, which provides implementation details for
  when/how to use the include_path to load translation file assets.
- Updated INI, gettext, and PHP loaders to extend AbstractFileLoader.
[#4766] Add docblock detailing how to set include_path flag

- Added to translator loader plugin manager
Remove constants

- Remove constants, per @DASPRiD
Allow unsetting cookie attibutes by resetting to null
fix small typos : punctuation mark
[#4778] Add zend-filter as optional dependency
More consistent interface: Add "return $this" to set*() methods that didn't already have them.
Fix issue where setExpires(0) works, but $expires=0 doesn't work in the constructor. Remove redundant input checking from constrcutor in favor of that offered by the set*() methods.
Make @var docblocs more consistent for cookie attributes. Only one of specified null.
Update Zend_Validate.php

The String "File '%value%' does not exist" was not translated correctly.
Add checks to see if we have a class to instantiate

Also added a special case for when we're mistakenly trying to instantiate an interface
[validator] Validate quoted local part of email addresses

 Test for validate quoted local parts following the RFC 5321
[validator] Validate quoted local part of email addresses

 Fix for the validator issue
Fix Ini class comment block

Fix Ini class comment block from "XML" to "INI" for documentation purposes.
Merge branch 'hotfix/4791'

Close #4791