Globalfix

[Cxarli]

The Globals example failed on the Php::GLOBALS["c"]["member"] part. This PR should fix that issue, and adds another example which shows what the bug was.

[robocoder]

In global.h, instead of adding force_update(), why not simply mark it as dirty (by clearing the _exists flag) and then call the existing update()?

Example:

    _exists = false;
    update();

    Value::set(index, value);