Support Steam-created improper q3key files

[keiyakins]

When installing and running Quake 3 from Steam, it "helpfully" puts the CD key into the q3key files for you. However, it does this using capital letters, which means it reads as invalid. The key is of course valid, once you retype it in lower case.

This is, to be clear, a bug in Steam, not ioq3. The behavior is the same with the id Software client build. But it might still be a nice enhancement to detect and repair this case.

[NuclearMonster]

yep, good idea

[kk1201]

Ope, I realised a bit late that its the Q3 vm ignoring #880 whenever you connect to a server running unmodified 1999 paks. Works ok in the menu, not in-game. I propose reading and writing the key to the filesystem in lowercase.