Big list of dependency-structure related improvements

[Avaq]

I found myself getting lost in all of the ideas about how the def API and dependency structure could change to account for many of the small problems encountered by the community. So here's a list:

• Having def take env as input, and letting env carry information on whether types should be checked:
  Ideas about env. sanctuary-def#74

• Merging with bilby for ad-hoc polymorphism:
  Ideas about env. sanctuary-def#74

• Waiting for def rather than env:
  Ideas about env. sanctuary-def#74 (comment)
  support esnext module format for tree-shaking purposes #246 (comment)
  sanctuary-def dependency #327 (comment)
  v1.0.0 #335 (comment)

• Splitting the library and sharing sanctuary-def as a peer dependency:
  sanctuary-def dependency #327 (comment)
  ADTs defined using S functions are compatible only with types known to S #262 (comment)

• Simplification of S.create:
  ADTs defined using S functions are compatible only with types known to S #262 (comment)

• Function namespaces:
  (Optionally) automated environment via namespaces sanctuary-def#137

• An inheriting version of S.create for module scopes:
  Module scoping  #479

• Allow for def to decorate an increased variety of functions:
  Defining functions that take no arguments or multiple at once sanctuary-def#180

• Unification of def and $Function:
  Defining functions that take no arguments or multiple at once sanctuary-def#180 (comment)

• Having every function take their own options as input, instead of a single create function:
  support esnext module format for tree-shaking purposes #246 (comment)
  support esnext module format for tree-shaking purposes #246 (comment)

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If you have write access, feel free to append anything I might have missed to this list. Otherwise, put it in a comment and I'll amend the list myself. Please don't use the comments to share any new ideas - feel free to open issue for them and I will reference them here.

[davidchambers]

Thank you for compiling this list, Aldwin. :)