multiply by a rational instead of dividing by an integer

[karlwessel]

Dividing symbolics by an integer returns a multiplication by a rational. This fix makes sure that it is handled the same when creating a Div.

This fixes issue #736.

[github-actions]

Benchmark Results

	master	b1c3832...	master / b1c3832...
overhead/acrule/a+2	0.96 ± 0.3 μs	0.988 ± 0.27 μs	0.972 ± 0.4
overhead/acrule/a+2+b	0.941 ± 0.26 μs	0.987 ± 0.29 μs	0.953 ± 0.38
overhead/acrule/a+b	0.264 ± 0.026 μs	0.268 ± 0.12 μs	0.984 ± 0.43
overhead/acrule/noop:Int	1.56 ± 0.01 ns	1.56 ± 0.01 ns	1 ± 0.0091
overhead/acrule/noop:Sym	27 ± 6 ns	27.5 ± 0.46 ns	0.981 ± 0.22
overhead/get_degrees/large_poly	0.156 ± 0.0093 s	0.432 ± 0.03 s	0.36 ± 0.033
overhead/rule/noop:Int	0.035 ± 0.023 μs	0.0364 ± 0.025 μs	0.963 ± 0.91
overhead/rule/noop:Sym	0.0337 ± 0.024 μs	0.0333 ± 0.023 μs	1.01 ± 1
overhead/rule/noop:Term	0.0332 ± 0.024 μs	0.0334 ± 0.024 μs	0.994 ± 1
overhead/ruleset/noop:Int	0.118 ± 0.034 μs	0.119 ± 0.037 μs	0.99 ± 0.42
overhead/ruleset/noop:Sym	0.125 ± 0.038 μs	0.12 ± 0.039 μs	1.05 ± 0.47
overhead/ruleset/noop:Term	5.06 ± 0.67 μs	4.78 ± 0.81 μs	1.06 ± 0.23
overhead/simplify/noop:Int	0.318 ± 0.009 μs	0.239 ± 0.033 μs	1.33 ± 0.19
overhead/simplify/noop:Sym	0.315 ± 0.0063 μs	0.247 ± 0.032 μs	1.28 ± 0.17
overhead/simplify/noop:Term	0.0508 ± 0.0056 ms	0.0486 ± 0.0028 ms	1.05 ± 0.13
overhead/simplify/randterm (+, *):serial	0.123 ± 0.011 s	0.124 ± 0.012 s	0.989 ± 0.13
overhead/simplify/randterm (+, *):thread	0.0701 ± 0.0055 s	0.0705 ± 0.0056 s	0.995 ± 0.11
overhead/simplify/randterm (/, *):serial	0.246 ± 0.023 ms	0.253 ± 0.022 ms	0.972 ± 0.12
overhead/simplify/randterm (/, *):thread	0.279 ± 0.027 ms	0.284 ± 0.03 ms	0.981 ± 0.14
overhead/substitute/a	0.106 ± 0.011 ms	0.105 ± 0.011 ms	1.01 ± 0.15
overhead/substitute/a,b	0.09 ± 0.01 ms	0.0909 ± 0.0069 ms	0.99 ± 0.14
overhead/substitute/a,b,c	20.2 ± 2.1 μs	20.1 ± 2.2 μs	1 ± 0.15
polyform/easy_iszero	0.0422 ± 0.0058 ms	0.0427 ± 0.0059 ms	0.989 ± 0.19
polyform/isone	3.1 ± 0.01 ns	3.11 ± 0.01 ns	1 ± 0.0046
polyform/iszero	1.43 ± 0.049 ms	1.43 ± 0.048 ms	1 ± 0.048
polyform/simplify_fractions	1.9 ± 0.094 ms	1.93 ± 0.14 ms	0.986 ± 0.087
time_to_load	1.13 ± 0.024 s	1.13 ± 0.0044 s	1 ± 0.022

Benchmark Plots

A plot of the benchmark results have been uploaded as an artifact to the workflow run for this PR.
Go to "Actions"->"Benchmark a pull request"->[the most recent run]->"Artifacts" (at the bottom).