Fixes to readPixel, drawChar + new readRect/writeRect

Hi Paul,

It would be great if you could merge in some/all of the changes I made to the ILI9341 library.

In particular: 
Fixed to drawChar - Problem with drawChar when using solid background color.  Before it was outputting more data than you set up in the setAddr call.  First attempt was to fix the setAddr call, which I did, but then was pointed out that the code was not outputting 9*size pixel lines per char instead of 8 as the old code and other branches did.  So I merged in recommended fix.

readPixel - Now works!

Found that using readPixel and pushColor or the like was quite slow, so I introduced a couple new methods, readRect/writeRect which does multiple.  Sped things up a lot.  Have test case which was posted.

Optional: I updated the spit bitmap test case to do it multiple times.  One time using the pushColor method and another using my writeRect function, which sped it up... 

Thanks Paul!

Kurt