make a combined target for both sorting algorithms:

[cfbolz]

• whether to use powersort or timsort is determined by a command line argument
• different copies of the sorting class are used, meaning the final binary contains all four variant
• the bool "powersort" is evaluated at compile time only, not at runtime
• we make the wrapped list at run time. that reduces the binary size and the compile time (and maybe sys time?)

(sending a mail about this too)