Plugins support

[ziflex]

The idea is to allow Ferret CLI load some custom FQL functions before any script execution. It might be useful for those, who use Ferret though CLI.

The possible commands are:

ferret plugin install fs

ferret plugin remove fs

ferret plugin search fs

ferret plugin info fs

Last 2 commands suppose having a centralized registry.

All plugins should be kept in $HOME/.ferret/plugins
I guess plugins should come as tar packages with some metadata written either in .json or .yaml file.