it compiles, but segfaults
fix segfault; results still not correct

Using left and right as absolute memory positions caused errors
in the recursive call. Fixed by making left and right relative
positions instead.
fix size in recursive call
remove superfluous copying

Temp array doesn't need to be initialized.
assert that result is sorted
add makefile
add usage message when called without arguments
add local .gitignore
Merge branch 'quicksort'