workspace refactor

[tjjfvi]

Refactors the repo into a workspace of several crates. Most of the functionality is left unchanged; though two things were removed, as continuing to support them would not be worth the complexity to keep them:

• the atomic fuzzer, and its tests, are removed (though it lives on in a gist)
• compiling to a standalone binary; only dylib compilation is supported now

I've squashed the history here, but for posterity: 239ec41

[HigherOrderBot]

Perf run for 61ef69b:

file              mode        main          61ef69b88ff4
========================================================
merge_sort        intr-singl       7.284 s       7.036 s
                  intr-multi       3.947 s       3.500 s
--------------------------------------------------------
sum_rec           intr-singl      14.233 s      14.319 s
                  intr-multi       7.397 s       7.218 s
--------------------------------------------------------
c2                intr-singl       0.000 s       0.000 s
                  intr-multi       0.001 s       0.001 s
--------------------------------------------------------
sum_tree          intr-singl       9.827 s       9.830 s
                  intr-multi       4.762 s       4.469 s
--------------------------------------------------------
radix_sort_lam    intr-singl       9.793 s       9.291 s
                  intr-multi       4.836 s       4.490 s
--------------------------------------------------------
bitonic_sort_lam  intr-singl      11.528 s      10.891 s
                  intr-multi       5.654 s       5.218 s
--------------------------------------------------------
boom              intr-singl       2.262 s       2.236 s
                  intr-multi       2.609 s       2.656 s
--------------------------------------------------------
sum_tail          intr-singl       1.205 s       1.190 s
                  intr-multi       1.203 s       1.547 s