Check performance of copying a sim

[cliffckerr]

Do benchmarking of running vs. copying sims of different types, and see if there are shortcuts that could be done. Copying should be slower than allocating but faster than creating, e.g.:

import numpy as np
import sciris as sc

n = int(1e8)

with sc.timer('alloc'):
    z = np.zeros(n)

with sc.timer('orig'):
    r = np.random.rand(n)

with sc.timer('np-copy'):
    q = r.copy()

with sc.timer('dcp'):
    t = sc.dcp(q)

alloc: 27.7 μs
orig: 0.373 s
np-copy: 0.105 s
dcp: 0.103 s