DateTimeFormatter: Add option to return invalid date string unfiltered

[marcguyer]

• add documentation for DateTimeFormatter. Addresses #58.
• add @todo notation in docblock for $format property
• add tests for new option

• [x] Are you fixing a bug?
  • [x] Detail how the bug is invoked currently.

$filter = new DateTimeFormatter();
$filter->filter('2013-31-31'); // throws exception

• [x] Detail the original, incorrect behavior. DateTimeFormatter::filter throws an exception in the event that the input is not a parsable date string
• [x] Detail the new, expected behavior.

$filter = new DateTimeFormatter();
$filter->setThrowInvalidDateException(false);
$filter->filter('2013-31-31'); // returns "2013-31-31"

• [x] Base your feature on the master branch, and submit against that branch.
• [x] Add a regression test that demonstrates the bug, and proves the fix.
• [x] Add a CHANGELOG.md entry for the fix.

[froschdesign]

@marcguyer This is a new feature because the exception was previously a desired result. Please use the develop branch instead.

[weierophinney]

This repository has been closed and moved to laminas/laminas-filter; a new issue has been opened at https://github.com/laminas/laminas-filter/issues/2.

[weierophinney]

This repository has been moved to laminas/laminas-filter. If you feel that this patch is still relevant, please re-open against that repository, and reference this issue. To re-open, we suggest the following workflow:

• Squash all commits in your branch (git rebase -i origin/{branch})
• Make a note of all changed files (`git diff --name-only origin/{branch}...HEAD
• Run the laminas/laminas-migration tool on the code.
• Clone laminas/laminas-filter to another directory.
• Copy the files from the second bullet point to the clone of laminas/laminas-filter.
• In your clone of laminas/laminas-filter, commit the files, push to your fork, and open the new PR. We will be providing tooling via laminas/laminas-migration soon to help automate the process.