Update English frontend locale

Update locale files

Refactor decimal separator to make Pas2C happy

Fix Pas2C failing to include SysUtils

Backed out changeset 13589d529899 So, we only disabled this on the release branch in r29d614a5c9eb due to having discovered it JUST before release. We should fix it properly in default...

Force-enable NOVIDEOREC when building PAS2C due to bug #722

Frontend: Slightly increase size+padding for QLineEdit, QSpinBox

Use Qt style "Windows", remove optional dependency on qtstyleplugins

Add explicit custom scroll bar style

Implement external events approach to input user actions into engine. Doesn't work for some obscure reason ("Error: Unknown method parameter type: LongEventType")