Utilize precompilable bigints

[ChrisRackauckas]

JuliaLang/julia#28296 (comment)

[coveralls]

Coverage increased (+0.5%) to 90.452% when pulling a904fa7 on bigints into 49559ca on master.

[codecov]

Codecov Report

Merging #95 into master will increase coverage by 2.84%.
The diff coverage is n/a.

@@            Coverage Diff            @@
##           master     #95      +/-   ##
=========================================
+ Coverage   87.75%   90.6%   +2.84%     
=========================================
  Files          33      34       +1     
  Lines        1160    1394     +234     
=========================================
+ Hits         1018    1263     +245     
+ Misses        142     131      -11

Impacted Files	Coverage Δ
src/tableaus.jl	100% <ø> (ø)	⬆️
src/perform_step/implicit_split_step.jl	58.33% <0%> (-12.92%)	⬇️
src/perform_step/kencarp.jl	77.77% <0%> (-5.56%)	⬇️
src/perform_step/sra.jl	96.42% <0%> (-2.26%)	⬇️
src/caches/sra_caches.jl	98.19% <0%> (-1.81%)	⬇️
src/perform_step/sdirk.jl	81.81% <0%> (-1.52%)	⬇️
src/misc_utils.jl	100% <0%> (ø)	⬆️
src/caches/kencarp_caches.jl	100% <0%> (ø)	⬆️
src/caches/implicit_split_step_caches.jl	100% <0%> (ø)	⬆️
... and 28 more

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