Render authored Descriptive Books and persist random Age seasons (#40)

src/main/resources/assets/rivencraft/lang/en_us.json

@@ -88,12 +88,16 @@
   "screen.rivencraft.book.unwritten": "This Descriptive Book is unwritten",
   "screen.rivencraft.age.title": "Age name",
   "screen.rivencraft.age.title_hint": "Name this Age",
+  "screen.rivencraft.age.unknown_author": "Unknown author",
   "screen.rivencraft.age.name_prompt": "Name this Age before writing the Descriptive Book",
   "screen.rivencraft.age.create": "Create",
   "screen.rivencraft.age.generator": "Terrain: %s",
   "screen.rivencraft.age.pages": "Pages",
   "screen.rivencraft.age.details": "Details",
   "screen.rivencraft.age.pages_count": "Writing %s/%s",
+  "screen.rivencraft.age.writing_notes": "Writing notes",
+  "screen.rivencraft.age.writing_general": "Book",
+  "screen.rivencraft.age.writing_page": "Page %s",
   "screen.rivencraft.age.trait.biomes": "Biomes: %s",
   "screen.rivencraft.age.trait.lighting": "Lighting: %s",
   "screen.rivencraft.age.trait.weather": "Weather: %s",