Add `showConsoleDebug` option

[Liooo]

The console warning shown here is usually very useful, but sometimes we want to suppress it (like in production).

This PR:

• adds showConsoleDebug option, which hides the console warnings when set to false (defaults to true, so this is backward compatible)
• bumps up the version to 2.1.0

[Liooo]

@kamilkp resolved conflict, plz merge if it's looking good

[mistic100]

@kamilkp please merge this feature. In my list I have merged top/bottom borders generating a 1px difference between the actual size and the computed size. This is not problem and should not spam the console. Thank you.