disable nbody_plusplus and move to the icebox
move nbody_temp to the icebox as well
move blackscholes_temp to icebox
Remove mandel -> mandelbrot indirection
mandel: update to use explicit iteration
nbody: re-import n-body program from accelerate-examples

This defaults to the good version of n-body, but include the old replicate/fold
version as well (although no longer selectable via command-line argument).

This adds the simple file parser to read the input positions from file, taken
from the previous implementation (in directory makefile_based).
nbody: move old version to the icebox
nbody: update makefile a bit
nbody: update individual benchmark programs
kmeans: add basic benchmark program
kmeans: add individual benchmark executables
add k-means to the benchmark runner script