Saving screenshot should provide message notifying user where it saved

[historic_bruno]

Currently when you take a screenshot in the game (F2), there is no message and the screenshot is silently saved to a certain directory, differing by the user's OS. A dialog is probably too much interruption for the user, as it's one more thing they'd have to click through, so a chat message / log entry seems a logical way to solve this.

[Philip Taylor]

One thing that always irritates me is when taking multiple screenshots, and the second one shows the "Saved screenshot0000.bmp" text from the first one. Not sure how best to avoid that, though. Maybe the screenshot key should hide any old screenshot messages and then call the renderer again (kind of like the big screenshot feature does) rather than simply dumping what's already on the screen?

[historic_bruno]

Good suggestion. To get around that I've added a GameSetup::RenderLogger function which allows the logger messages to be temporarily hidden. Also added a CLogger::LogMessageRender function and macro, to render a normal message when we want.

[ben]

(In [8675]) Add screenshot location logging w/ rendered console message. Rendered messages are hidden before screenshot is taken. Fixes #675