Do not make AbstractHistoryFunction <: Function

[ChrisRackauckas]

This effects Julia's specialization heuristics in undesirable ways. See https://discourse.julialang.org/t/delay-differential-equations-networks-with-different-delay-per-edge/69787

[codecov]

Codecov Report

Merging #110 (67e24a8) into master (e6781a3) will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff           @@
##           master    #110   +/-   ##
======================================
  Coverage    6.78%   6.78%           
======================================
  Files          39      39           
  Lines        2904    2904           
======================================
  Hits          197     197           
  Misses       2707    2707           

Impacted Files	Coverage Δ
src/SciMLBase.jl	0.00% <ø> (ø)

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[devmotion]

Maybe dropping Function supertypes is helpful for other types such as

SciMLBase.jl/src/SciMLBase.jl

Line 273 in fcd581d

abstract type AbstractDiffEqInterpolation <: Function end

as well?

[ChrisRackauckas]

yeah it's probably a good idea.