Add indicator to show if saving succeeded or failed

[MechaTech84]

Currently it isn't obvious if saving a lab/file succeeded or failed. I think there should be some feedback so it is.

I'm thinking on successful saves some black text would appear saying "Saved!" and then after some time fade out.

For failed saves, red text would appear saying "Error Saving!" and then after some time fade out.

I also suggest that clicking save disables the button until a small delay, maybe 500ms, after feedback is shown.

My suggested locations for the text are shown below:

[paj28]

This sounds like a good idea