Add safeSet for children & collections

[pgilad]

• Closes Provide namespace collision errors ampersand-view#128
• Closes Namespace collision warnings ampersand-view#96

[kamilogorek]

Are we sure that we want to throw when it happens instead of just inform dev?

[pgilad]

My thoughts are that if you're doing something wrong (which will cause errors down the line), throw loudly. I'd rather have that than a console.log.

[cdaringe]

+1

[lukekarrys]

+1