T/85: Use a simpler plugin naming scheme

[pomek]

Suggested merge commit message (convention)

Feature: PluginCollection will warning if a user wants to load two or more plugins with the same name. Closes ckeditor/ckeditor5#2914.

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Additional information

• List of packages that plugins have changed their names: https://github.com/ckeditor/ckeditor5-core/issues/85#issuecomment-312517286, https://github.com/ckeditor/ckeditor5-core/issues/85#issuecomment-312551986.
• Build on CI which uses new plugin names.

[Reinmar]

I think that this change is overcomplicated.

There's one place where every loaded plugin must be passed through – the _add() function. Add a warning there and it will be a 3 LOC change.

[pomek]

What about the constructor and availablePlugins? Is it also should be checked?

[Reinmar]

What about the constructor and availablePlugins? Is it also should be checked?

The question is – what we want to check. And the answer is – whether there are some duplications between loaded plugins. Why checking anything else? Always do the minimal thing but not less.

[pomek]

@Reinmar, could you look it now? I simplified the code a bit.

[Reinmar]

log.warn() should not be used with a dynamically set message because it's designed to be shortened during building (hence, it needs an id).

Also, you forgot to update the PluginInterface.pluginName documentation.

I'm on it.

[pomek]

Thx for helping.

[Reinmar]

There were some outdated plugin names used in manual tests of the clipboard and upload packages.