* Add grouping of preconditions to allow for flexible precondition logic.
* Fix checking Module Preconditions twice (and none of the command's own)
* Fix command preconditions group 0 looping over every other precondition anyway #whoopsies
* Use custom message when a non-zero Precondition Group fails.
* Fix doc comment rendering.
* Refactor loops into local function
* Considering a new result type
* Switch to IReadOnlyCollection<T> and fix compiler errors
* Revert PreconditionResult -> IResult in return types - Change PreconditionResult to a class that PreconditionGroupResult inherits.
* Feedback on property name.
* Change grouping type int -> string
* Explicitly use an ordinal StringComparer
* Full stops on error messages
* Remove some sillyness.
* Remove unneeded using.
