Indicate which modes are active when loading in to gameplay

[InfoTeddy]

Many times I (and many others) have forgotten that we have, say, invincibility mode enabled when loading in. There should be text onscreen in the upper-left saying "Invincibility mode enabled" that fades out after a few seconds.

Ditto for other modes that might not be immediately obvious to the user, like glitchrunner. (Flip Mode and slowdown should be sufficiently obvious that they don't need to be indicated should be indicated too for consistency.)