Reloading big pages: console is cleared *after* log output

[smilingthax]

When reloading a bigger page with active chrome logger, the console first displays the chromelogger log data and then clears itself.
While "Preserve Log upon Navigation" keeps the data, the objects are not expandable any more.

The underlying problem is, that the old content script receives the messages from the background page.

Fix: In log.js, function _init() add:
window.addEventListener('beforeunload', _stopListening);