Set-theoretic types: inference of all language constructs

[josevalim]

Major milestones:

• Tracking of variables
• Type inference of patterns
• Type inference of guards
  • Propagate types from guards to patterns
  • Deal with multiple environments in orelse/andalso
  • Deal with multiple environments in or/and
  • Deal with multiple environments in when
  • Inference of equality
• Type inference for function application and function definition
• Type inference of return types

This is a more granular break down of what needs to be done:

• Map and struct updates
• Checking of all inlined functions from Kernel
• Checking of all inlined conversion functions
• Checking of __STACKTRACE__ and raising functions
• Support for local calls
• Support for remote calls
• Support for __info__, module_info, and behaviour_info
• Typing of :erlang inlined functions
• for comprehensions
  • generators
  • :into
  • :reduce
• Detect never matching clauses and patterns (cond, case, try)
• Improve pretty printing of negations
• Track precision
  • case
  • receive
  • try
  • definitions
  • with
  • reduce
  • fun
• Track conditional variables
  • case
  • cond
  • receive
  • try
  • with
  • reduce
  • fun
• Reverse arrows
  • with
  • case
  • cond
• Inference of default args
• Infer based on all loaded applications
• Unused clauses in private functions
• Tracking of mismatches in equality operators
• Tracking of structs in ordered comparison operators
• Move compile.protocols to parallel compiler
• Type checking of protocol dispatch
• Type checking of impls
• Storing of inferred types in .beam files
• Infer all Elixir modules at once

This was extracted from #13227 and will be followed up by #15127 and #13881.