Added new min, max variadic operators
Added common collection-access utilities in Operation
Added common collection-access utilities in Operation
Parser now accepts single-argument expressions as potentially variadic
Fixed typo in class-name
Made all variadic operators collection-aware (via 1 collection argument)
* made xor variadic
* added tests
Post-review fixes:
- using ArrayReflection everywhere (CollectionSize and GetFromCollection included)
- better naming for Literals used in Operation iterators
- using your improved condition check in the parser
Merge pull request #592 from manuel-freire/add-min-max-operators

Added new min, max variadic operators