[#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
[#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
Annotate expires may be a string or an int
Add unit tests for changes SetCookie behavior
default mode variables from static:: constants