Allow to use negative values with the drush mw-reorder command

Problem/Motivation

If you read How to use negative number as argument value in a drush command? you will see that at this moment is not possible to use a negative value as argument, but for the drush mw-reorder command this is very important because the weight can be a negative integer.

Proposed resolution

Add a command option to allow negative values in the drush mw-reorder command.

Setting the onlyone module weight to -5.

drush mw-reorder onlyone 5 --minus

Remaining tasks

None.

User interface changes

None.

API changes

Added the --minus option to the drush mw-reorder command

Data model changes

None.