Use direct access instead of sending messages to background page & some fixes.

Instead of sending & receiving messages to the background page just use the background page variables to access them directly and restructured getPassword() function to not need callback-style usage.

Added Singapore "com.sg" to the TLD's we check for since it was requested from the Chrome Store's feedback page.

Trying to fix blank used text issue.

PS You've mis-spelled algorithm as algorythm on your description of this Repo and on the https://chrome.google.com/webstore/detail/passwordmaker-pro/ocjkdaaapapjpmipmhiadedofjiokogj/details page, might want to fix them unless thats how you spell it in German?