Change "with...do" method name to "using()do..."
Standardise on using()do-style methods

These methods behave like the existing using()do()blockWidth()...
method. using()times(n)do will run the block n times, and parallels
over()numbers()do()size. using()do infers the number of times to run by
the size of the largest input floatArray.
Rename matrix samples to explain them better