Fix some completion issues on the Editor (issue #2352)

[blink1073]

Fixes #2352.

[ccordoba12]

Thanks a lot for the ultra fast response ;-) I verified that all errors I found are fixed now!

There is one last thing I forgot to mention in issue #2352. When you write

import <Tab>

the full list of modules is not returned now, while it was before.

Would you mind to fix this also as part of this PR? Thanks :-)

[blink1073]

Fixed!

[ccordoba12]

Thanks, it's working now :-)

There is yet another thing I just find out. We should use the new module icon only when doing

import fo<Tab>

or

from ba<Tab>

but not when doing

from foo import ba<Tab>

because that shows every completion as a module, which is obviously wrong :-)

If in this last case our completion libraries can't introspect types (as I think it's the case), we need to show no icons at all :-)

[blink1073]

Okay, now we get icons for import nu<Tab> and from nu<Tab>, but not from numpy import a<Tab>.

[blink1073]

(unless you have Jedi of course 😄)

[ccordoba12]

Great work man!! Merging :-)