Multiplex refinements: filters

The porpoise of this request is to bring improvement regarding multiplex filters.

Currently the *global filters* (those passed in the command line `--filter-only` and `--filter-out`) are implemented at the multiplex level. Now we are going to use this function `apply_filters()` with other support changes, to make the global filters performs at the tree node structure, so it will bring to the plugin multiplexer, the feature to displays the tree structure with filters doing their job.

For the current state of the code, the *local filters* are broken (those inside the nodes in the YAML file), so it's better to keep it disable for now.