Multiple languages specific editor settings

We definitely need the ability to set those for multiple languages at once.

Something like:
```
// Once for all
"[cpp, c]":{
    "editor.formatOnSave": true
}
```

Instead of:
```
// Once for C++
"[cpp]":{
    "editor.formatOnSave": true
},

// And once for C
"[c]":{
    "editor.formatOnSave": true
}
```
