Clean up import order.

One-line docstring should not occupy 3 lines
Expected 1 blank line *before* class docstring
First line should end with '.'
Blank line missing between one-line summary and description
No blank lines allowed *after* method docstring
Use r""" if any backslashes in a docstring

Use CapWords convention for class names
Use new-style classes
Use lowercase with underscore for function and local variable names
(to be continued)

Use format() instead of % method.

- remove obsolete code
- glances_password: update comments and fix typos
- re-apply fix to avoid string format conflicts (screwed up after
  feature branch merges)
- strip trailing whitespaces
- flake8

Add args visibility to the plugins to handle with the SNMP server properties (address, community...)

Move 'idle' back to the first column (non-optional) because
is available on all platforms supported by Glances/psutil.

In the second column (optional), attributes are now sorted by
descending order of availability (they are depending on the platform).

Mandatory only for multi-line continuation

Explicit is better than implicit.