Potential BC break from new layout option

[rossmotley]

In #1044 a new layout option was introduced. This caused a breaking change for us because one of our form types was already setting a layout view variable in \Symfony\Component\Form\FormTypeInterface::buildView.

[isometriks]

Hmm. That is unfortunate that it collides like that. We probably could have / should have prefixed some of the options with mopa_ but now I feel like it's more of a BC break to change them now. Realistically not many people are probably using it but in the case where somebody has extended the form templates it could cause a break for them.

Can you just change your view variable to something else and fix it in your project? You can also still use ~3.1.0 as your composer restriction for this bundle as well. I don't believe there's really anything else important in 3.2 that you would need to upgrade for unless you want to use the new layout stuff?

[rossmotley]

@isometriks Perhaps adding a PHP notice/warning if there's a layout view variable already would be worth doing.

I guess it also would be good add a warning to the text at https://github.com/phiamo/MopaBootstrapBundle/releases/tag/v3.2.0 and perhaps https://github.com/phiamo/MopaBootstrapBundle/blob/master/CHANGELOG.md too.

For our project we've already resolved it by changing the names of our variables.