Make server aware of new versions

Rework of No Gravity script: - Now called Gravity, gravity is derived from get away time percentage in game scheme - Watchdog which sets gravity to normal when TurnTimeLeft is frozen for more than 15 seconds

Remove some wtfism that was breaking localisation

Recover old tips from .ts files. This addresses bug #740

Pick random tip from the tip file each time front page is viewed.

Localise tips again. Including new german contribution from bug #738. We should look into the old .ts files and see if there are translations that can be recovered.

typos correction

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'Open packages directory' button on dlc page

merge of volkan's commit followed by lupdate to pick up the new strings