[#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
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
Fix showdecimals Issue when viewhelper is executed sequentially
according to http://www.jsonrpc.org/specification#error_object the error code for parse error is -32700
catch exception when parsing malformed JSON and set property
check for parse error property on request
added test case, formatting