Micro-optimization: faster split_selfies

[rhjohnstone]

Just for fun, I implemented sf.split_selfies slightly differently, which is 2--4x faster on the selfies I tested. These are valuable microseconds we're saving!

All tox tests pass, and I added a new test to confirm correctness and benchmarks comparing the two split methods against 3 different datasets: a list of regular selfies, a list of selfies containing a dot, and a list of much longer selfies. Here are the benchmarks from the 3.10 tests, and they all look like this:

------------------------------------------------------------------------------------------------------ benchmark 'dots': 2 tests ------------------------------------------------------------------------------------------------------
Name (time in us)                                               Min                   Max                Mean             StdDev              Median         
       IQR            Outliers  OPS (Kops/s)            Rounds  Iterations
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
test_compare_split_methods[split_selfies-dots]              89.3000 (1.0)        719.9000 (1.0)       96.9626 (1.0)      23.3265 (1.0)       91.8000 (1.0)       2.4000 (1.0)       490;936       10.3133 (1.0)        8681           1
test_compare_split_methods[_split_selfies_legacy-dots]     237.8000 (2.66)     1,235.5000 (1.72)     259.4146 (2.68)     63.0037 (2.70)     245.2000 (2.67)     12.7000 (5.29)      142;249        3.8548 (0.37)       2646           1
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

-------------------------------------------------------------------------------------------------------- benchmark 'long': 2 tests ---------------------------------------------------------------------------------------------------------
Name (time in us)                                                 Min                   Max                  Mean              StdDev                Median                IQR            Outliers         OPS            Rounds  Iterations
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
test_compare_split_methods[split_selfies-long]               340.3000 (1.0)      1,156.1000 (1.0)        365.6551 (1.0)       69.9039 (1.0)        350.9000 (1.0)      10.9000 (1.0)       116;287  2,734.8174 (1.0)        2422           1
test_compare_split_methods[_split_selfies_legacy-long]     1,307.6000 (3.84)     2,920.7000 (2.53)     1,405.9733 (3.85)     193.6538 (2.77)     1,353.0500 (3.86)     69.4000 (6.37)        54;85    711.2511 (0.26)        726           1
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

----------------------------------------------------------------------------------------------------- benchmark 'regular': 2 tests ----------------------------------------------------------------------------------------------------
Name (time in us)                                                  Min                 Max                Mean             StdDev              Median               IQR            Outliers  OPS (Kops/s)            Rounds  Iterations
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
test_compare_split_methods[split_selfies-regular]              51.4000 (1.0)      285.1000 (1.0)       58.4986 (1.0)      15.8357 (1.0)       54.9000 (1.0)      2.0000 (1.0)      755;1375       17.0944 (1.0)       12346           1
test_compare_split_methods[_split_selfies_legacy-regular]     117.9000 (2.29)     943.0000 (3.31)     130.6158 (2.23)     26.6549 (1.68)     124.8000 (2.27)     5.5000 (2.75)      481;798        7.6560 (0.45)       7687           1
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

[MarioKrenn6240]

Thank you. Give us some time to check and comment.