UMD Build: Slots groupOperator and groupControl cannot be used #103
Description
With VueJs Version 2.6.14 and when using the file "query-builder-vue.umd.min.js":
Slot "rule": works fine
Slot "groupOperator": not usable, because it is has a camelCase name
Slot "groupControl": not usable, because it is has a camelCase name
My current workaround is a simple renaming of the slot names directly in the build file: groupOperator -> groupoperator and groupControl -> groupcontrol
CamelCase seems to be an issues / not allowed in some cases