Implement key data model

- Added classes for Person, Gender, Family, FamilyTree
- Replaced FamilyTreeManager with FamilyTree
- Add FamilyFactory for seeding the initial FamilyTree for King Arthur and Queen Margaret
- Added a RelationshipManager for linking spouses correctly
- Refactored ActionFileExecutor for readability
- More test coverage

1 files changed, 16 insertions, 0 deletions

diff --git a/lib/gender.rb b/lib/gender.rb
new file mode 100644
index 0000000..9bd3b06
--- /dev/null
+++ b/lib/gender.rb
@@ -0,0 +1,16 @@
+# frozen_string_literal: true
+
+class Gender
+  MALE = 'male'
+  FEMALE = 'female'
+
+  def self.all
+    [MALE, FEMALE]
+  end
+
+  def self.valid?(gender)
+    return false unless gender.is_a?(String)
+
+    all.include?(gender.downcase)
+  end
+end