Set shared library on if so requested.

conanfile.py

@@ -19,6 +19,9 @@ class CreatureLibConan(ConanFile):
         if self.settings.os == "Windows":
             self.output.warn("Noticed Windows target, setting Cmake WINDOWS=On.")
             cmake.definitions["WINDOWS"] = "On"
+        if self.options.shared:
+            self.output.info("Building shared library.")
+            cmake.definitions["SHARED"] = "On"
         if self.options.staticC:
             self.output.info("Linking C libraries statically")
             cmake.definitions["STATICC"] = "ON"