Add builtin just once

[mmatera]

This PR is one possible implementation for the @rocky 's idea that builtins (and autoload modules) should be loaded just once.

[rocky]

As i mentioned in another PR, let me suggest some code and you can review. Thanks.

[mmatera]

Ok. This was just to illustrate the point.

[rocky]

Ok. This was just to illustrate the point.

Ok. My takeaway with this is that there is some misunderstanding.

[TiagoCavalcante]

@mmatera just 2 Git tips:

• to not make the Git history complicated with merge commits you can use git rebase branch_name instead of git merge branch_name
• when things get complicated you can rewrite the history selecting only the commits you really want: git log, git checkout master, git checkout -b branch_name_new, and then for each commit you want to be in the branch branch_name do git cherry-pick commit_SHA, git branch -D branch_name, git branch -m branch_name and finally git push -f

[mmatera]

@mmatera just 2 Git tips:

* to not make the Git history complicated with merge commits you can use `git rebase branch_name` instead of `git merge branch_name`

* when things get complicated you can rewrite the history selecting only the commits you really want: `git log`, `git checkout master`, `git checkout -b branch_name_new`, and then for each commit you want to be in the branch `branch_name` do `git cherry-pick commit_SHA`, `git branch -D branch_name`, `git branch -m branch_name` and finally `git push -f`

@TiagoCavalcante thanks, and sorry for the noise. In any case, my mistake here was to put this in a PR instead of just cite the branch in the parent PR. The aim of this was just to understand @rocky 's idea.