changing the default scan rate to 100Hz

Thanatermesis (via email) told me that this worked for him, fixing his
issue of having some keys unexpectedly double tap (though, I think he
might have gone down to 50Hz, or something).  since he mentioned it,
i've been noticing my keys double tapping sometimes (on one of my brown
boards, with an acrylic case... it didn't seem to happen at all with my
blue caseless board...), so i decided to give this a try :)