remove bundle inheritance

[Hanmac]

Symfony 3.4 dropped bundle inheritance, the created bundles should not need it

I am targeting this branch, because it is probably not backwards compatible?

if otherwise, i will rebase it

Closes #152

Changelog

### Removed
- removed Bundle inheritance

Subject

[greg0ire]

@Hanmac this is not a bc-break, please retarget your branch. If this is merged and I update, there will be not break in my code, since this is just about code generation.

[Hanmac]

@greg0ire i think the code/branch got rebased as you want it to 2.x don't know what about that flintci or coverage thing

[greg0ire]

Don't worry about those

[Hanmac]

@core23 what would be the best Break note?

currently my idea is like this:

### Deprecated

Generated Bundles no longer use Bundle inheritance, because Symfony dropped the support for this in 3.4+ [symfony blog](https://symfony.com/blog/new-in-symfony-3-4-deprecated-bundle-inheritance)
If You really need it, you can add it yourself.

[jordisala1991]

Ping @Hanmac

Please rebase, and add the upgrade note and answer my question: And what about If I am using Symfony 2.8 and generate this bundle without inheritance?

And then we can merge

[Hanmac]

@jordisala1991 what branch should I rebase from? 2.x or master? (Please Devs choose)

Is my update note good this way?

For 2 8, if you create a bundle without inheritance it wouldn't make any change for most of the uses because the bundle inheritance is ignored or deprecated for any use. (Check the blog link)

[jordisala1991]

2.x and the upgrade note should be good but you need to add it to the file @core23 said

[greg0ire]

Thanks @Hanmac !