o main returns int not void
o use return 0 at end of main when needed
o use braces to avoid potentially ambiguous else
o don't default to type int (and also remove a useless register
modifier).
Reviewed by: obrien and chuckr
This will make a number of things easier in the future, as well as (finally!)
avoiding the Id-smashing problem which has plagued developers for so long.
Boy, I'm glad we're not using sup anymore. This update would have been
insane otherwise.
