Alter PHPUnit_Util_Type::recursiveExport() to handle repeated and recursive
data structures more gracefully (and with less memory usage).
Remove the ReflectionObject stuff and hang off ::toArray(), since it handles
undeclared properties correctly.
Add ExportContext.php to the package.xml.
Change recursiveExport() output to be closer to what was previously there.

Specifically, we don't want to move to a newline for the leading line of
exported arrays and objects, and we don't want a newline before the opening
parenthesis.
Reinstate the previous CRLF folding behaviour in recursiveExport().
Remove more extraneous newlines.
Update object properties to be single quoted as well.
Use self::export() for array and property keys as the old code did.
Update the recursiveExport() output to better match the old behaviour.
Update PHPUnit_Util_Type tests to handle the new output format of
recursiveExport().
Update constraint tests for the new recursiveExport() output format.
Fix dates and version numbers.
Merge pull request #773 from LawnGnome/recursive-export