Find a better location for the src/app/gui/vue folder

[Raruto]

That folder contains configuration files that can deeply modify the application and therefore essential to understand how it works in detail, also for this reason it would be better to place them in a less nested position.

As per 68da69f (v3.4) this is the situation:

.
└── src/
    ├── app/
    │   ├── core/
    │   ├── g3w-ol/
    │   └── gui/
    │       └── vue/
    │           ├── global-components/
    │           │   └── ...
    │           ├── utils.js
    │           ├── vue.directives.js
    │           ├── vue.filter.js
    │           ├── vue.globalcomponents.js
    │           ├── vue.mixins.js
    │           └── vueapplugin.js
    ├── config/
    └── plugins/

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Below is an example of how it might become (directives, filters, mixins):

[Raruto]

As per v3.8.0-alpha.1, the src/app/gui/vue folder no longer exists.

As for refactoring the gui folder, continue the discussion in here: #193