Modify mixin to handle factories, init functions, and aspects

[maier49]

This also returns chained init functions to their original
order, so that if you call A.mixin(B), A's init function
will run before B's.

[codecov-io]

Current coverage is 100.00%

Merging #21 into master will not affect coverage as of dac4d0a

@@            master     #21   diff @@
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  Files            2       2       
  Stmts          171     178     +7
  Branches        22      26     +4
  Methods          0       0       
======================================
+ Hit            171     178     +7
  Partial          0       0       
  Missed           0       0       

Review entire Coverage Diff as of dac4d0a

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[kitsonk]

I am going to move this over to the tersemixin feature branch, as I think we might want to do some more work/iteration on the API. I have some ideas based on the thoughts in #22.