Add DispatchDoctor.jl and fix various type instabilities

[MilesCranmer]

To be merged after #73

[github-actions]

Benchmark Results

	master	7eda0fe...	master/7eda0fe691bceb...
eval/ComplexF32/evaluation	7.45 ± 0.49 ms	7.7 ± 0.49 ms	0.968
eval/ComplexF64/evaluation	9.69 ± 0.74 ms	9.75 ± 0.68 ms	0.994
eval/Float32/derivative	10.9 ± 1.9 ms	10.9 ± 1.8 ms	0.998
eval/Float32/derivative_turbo	10.9 ± 1.9 ms	10.8 ± 1.9 ms	1.01
eval/Float32/evaluation	2.75 ± 0.22 ms	2.73 ± 0.22 ms	1.01
eval/Float32/evaluation_bumper	0.598 ± 0.013 ms	0.575 ± 0.013 ms	1.04
eval/Float32/evaluation_turbo	0.71 ± 0.032 ms	0.704 ± 0.028 ms	1.01
eval/Float32/evaluation_turbo_bumper	0.595 ± 0.013 ms	0.578 ± 0.013 ms	1.03
eval/Float64/derivative	14.4 ± 0.78 ms	14.6 ± 0.85 ms	0.981
eval/Float64/derivative_turbo	14.3 ± 0.73 ms	14.4 ± 0.64 ms	0.993
eval/Float64/evaluation	2.9 ± 0.24 ms	2.94 ± 0.24 ms	0.987
eval/Float64/evaluation_bumper	1.27 ± 0.042 ms	1.3 ± 0.044 ms	0.981
eval/Float64/evaluation_turbo	1.19 ± 0.062 ms	1.2 ± 0.065 ms	0.984
eval/Float64/evaluation_turbo_bumper	1.27 ± 0.045 ms	1.3 ± 0.044 ms	0.977
utils/combine_operators/break_sharing	0.0419 ± 0.0013 ms	0.0413 ± 0.0013 ms	1.01
utils/convert/break_sharing	28.2 ± 1.1 μs	29.8 ± 0.96 μs	0.947
utils/convert/preserve_sharing	0.128 ± 0.0033 ms	0.127 ± 0.0029 ms	1
utils/copy/break_sharing	29.1 ± 1.1 μs	29.4 ± 0.92 μs	0.992
utils/copy/preserve_sharing	0.127 ± 0.0032 ms	0.126 ± 0.0031 ms	1.01
utils/count_constants/break_sharing	11 ± 0.18 μs	10.6 ± 0.16 μs	1.04
utils/count_constants/preserve_sharing	0.111 ± 0.0027 ms	0.111 ± 0.0025 ms	0.999
utils/count_depth/break_sharing	17 ± 0.38 μs	17.6 ± 0.35 μs	0.968
utils/count_nodes/break_sharing	9.68 ± 0.17 μs	9.91 ± 0.17 μs	0.976
utils/count_nodes/preserve_sharing	0.114 ± 0.0026 ms	0.113 ± 0.0025 ms	1
utils/get_set_constants!/break_sharing	0.053 ± 0.00083 ms	0.0521 ± 0.00077 ms	1.02
utils/get_set_constants!/preserve_sharing	0.321 ± 0.0064 ms	0.321 ± 0.0072 ms	0.998
utils/has_constants/break_sharing	4.58 ± 0.21 μs	4.43 ± 0.22 μs	1.04
utils/has_operators/break_sharing	2.1 ± 0.018 μs	1.75 ± 0.018 μs	1.2
utils/hash/break_sharing	0.0326 ± 0.00046 ms	0.0325 ± 0.00048 ms	1
utils/hash/preserve_sharing	0.136 ± 0.0026 ms	0.135 ± 0.0029 ms	1.01
utils/index_constants/break_sharing	27.2 ± 0.72 μs	27.3 ± 0.73 μs	0.995
utils/index_constants/preserve_sharing	0.128 ± 0.003 ms	0.128 ± 0.0029 ms	1
utils/is_constant/break_sharing	4.52 ± 0.22 μs	4.77 ± 0.22 μs	0.948
utils/simplify_tree/break_sharing	0.156 ± 0.016 ms	0.152 ± 0.015 ms	1.02
utils/simplify_tree/preserve_sharing	0.288 ± 0.018 ms	0.265 ± 0.017 ms	1.09
utils/string_tree/break_sharing	0.506 ± 0.014 ms	0.388 ± 0.013 ms	1.31
utils/string_tree/preserve_sharing	0.646 ± 0.018 ms	0.535 ± 0.019 ms	1.21
time_to_load	0.219 ± 0.0038 s	0.223 ± 0.0026 s	0.98

[coveralls]

Pull Request Test Coverage Report for Build 9359315057

Details

• 48 of 48 (100.0%) changed or added relevant lines in 9 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.09%) to 95.35%

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Totals
Change from base Build 9358888457:	0.09%
Covered Lines:	1866
Relevant Lines:	1957

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💛 - Coveralls