Rewrite Log service

[renatomassaro]

This will be a rather large PR meant to enhance (but mostly rewrite) the Log service.

The biggest improvement is that now logs are structured data with pre-defined types, as opposed to the old Log system who was simply a string, void of any context.

So we changed from:

String: "localhost downloaded file Cracker.crc (1.0) from 1.2.3.4"

to

Struct: {type: :download_gateway, file_name: "Cracker.crc (1.0)", ip: "1.2.3.4", network_id: "::"}

To the end user this change is transparent (the struct will be "translated" to the string above anyways). But this allows for:

• easier/better i18n support
• enhanced log editing support / UI
• easier support on log-based features (e.g. Log X should have field Y updated to contain Z)

---

• Support structured Log format
• Rewrite Log internals
• LogPaginateRequest
• LogFilterRequest
• LogIndex
• LogHenforcer
• LogForgeRequest
  • LogForgeHenforcer
• LogFactor
• LogForgeProcess
  • Create
  • Edit
• LogRecoverRequest
  • LogRecoverHenforcer
• LogRecoverProcess
  • Global
  • Custom
• LogAddedEvent
• LogRecoveredEvent
• LogRevisedEvent
• LogDestroyedEvent

Incidental

• Removed LogFactory
• Completely removed ex_machina dependency 🎉
• Added tgt_log_id on Process.t struct
• Added set_relay/3 macro for Helix.Factor
• Added SIGRETARGET, i.e. support for recursive process type (Support different types of processes lifecycles on TOP #324)
• Added custom pre-hook at Process.Executable

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This change is 

[sourcelevel-bot]

Ebert has finished reviewing this Pull Request and has found:

• 5 possible new issues (including those that may have been commented here).
• 6 fixed issues! 🎉

You can see more details about this review at https://ebertapp.io/github/HackerExperience/Helix/pulls/410.