Describe the feature

make SlotSemantic not an enum and make the constructor public

Reasons why it should be considered

it would allow addons to add their own slots using their own names for those slots
currently, addons have to use other existing SlotSemantics, whose names really don't fit (in most cases)
and they are limited to the amount of slottypes (although I am not sure why anyone would add that much slots)

Additional details

No response