* MM-14442: Merge function, to enable merging of configs
Merge will return a new struct of the same type as base and
patch, with patch merged into base. Specifically, patch's values will be preferred
except when patch's value is `nil`.
Restrictions/guarantees:
- base or patch will not be modified
- base and patch can be pointers or values
- base and patch must be the same type
- base and patch must have no unexported types (at the moment)
- if maps or slices are different, the entire map or slice will be
replaced (at the moment)
* License header
* major rewrite addressing PR comments from Jesse
* MM-14442: merge function for config files
- simplified merge for slices and maps
- fixed many problems with nested pointers/maps/slices
- all references are cloned
- 54 new tests, simplified tests for specific problems
* MM-14442: fixing formatting, comments
498b988a6b