Fixes XML string escaping by removing invalid characters
Show stack trace for unexpected exceptions.
Show stack trace even with no message; added test case.
Replace PHPUnit_Util_Diff with SebastianBergmann\Diff
Skip this test for now
Use callable type hint
Replace PHPUnit_Util_Type with SebastianBergmann\Exporter
Fix
Set the `minimum-stability` to `dev` for the master branch as it requires dev versions of `phpunit/php-timer`, `sebastian/diff`, and `sebastian/exporter`.
Simplified the travis config file a bit.
Merge pull request #821 from whatthejeff/composer-minimum-stability
Merge pull request #822 from whatthejeff/simplify-travis
Also test with PHP 5.5
Revert "Also test with PHP 5.5"

This reverts commit 1af126c4066e340f0c4e3e66d276d85dda24ea7e.
Attempt at backporting composer.json and .travis.yml changes from master
Fixes #823

 * `PHP_BINARY` needs to be escaped before used in shell commands.
Fixes #823

 * Use `escapeshellarg()` instead of `escapeshellcmd()` for escaping the binary name.
Merge pull request #824 from whatthejeff/issue_823
Merge pull request #825 from whatthejeff/issue_823_37
Update tests for new update from PHP_Timer