Prevent using the same component multiple times in any operations, through panic

[mlange-42]

Disallows things like these:

e := world.NewEntity(posID, posID) // add the same thing twice
world.Exchange(e, []ID{posID}, []ID{posID}) // add and remove the same thing

Which would have caused bugs when used.

Fixes #349

[coveralls]

Pull Request Test Coverage Report for Build 7750171565

• 0 of 13 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

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Totals
Change from base Build 7750012433:	0.0%
Covered Lines:	6159
Relevant Lines:	6159

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💛 - Coveralls