##### Summary
This PR adds (major) changes only to `python.d.plugin` file.
Fixes: #5525
`pyhton.d.plugin` imports a lot of additional packages during initial module initialization/job creating/checking and there is no way to unimport them, even if they arn't needed. It consumes relatively a lot of ram.
___
Memory utilization comparing before/after the PR (one job `example` module, py3.7.2):
> 21.1 => 8.8 MiB
##### Component Name
[`collectors/python.d.plugin`](https://github.com/netdata/netdata/blob/master/collectors/python.d.plugin/python.d.plugin.in)
##### Additional Information
This PR adds separate process for initial module checking.
Logic:
- main process spawns checker process
- checker process loads every module, loads module config, creates jobs and runs job.check() for every job, if check success it adds the job to the list.
- checker process returns list of modules and jobs.
- main process loads only active modules, etc.
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##### Summary
Fix: #4756
`python.d.plugin` updates:
* remove `retries` option
* make `penalty` configurable (enabled by default, max is 10 minutes)
> penalty indicates whether to apply penalty to update_every in case of failures.
> Penalty will increase every 5 failed updates in a row. Maximum penalty is 10 minutes.
> penalty: yes
##### Component Name
`python.d.plugin`
##### Additional Information
* fix make dist; fixes#4400
* added daemon dir
* fix edit-config in dist
* removed config.h from file dependencies
* do not attempt to detect stock files on vanilla installations
* add missing files to dist
* another fix for missing dist files
* modular plugins are now self-configured for automake
* updated lgtm
* fix cncf urls
