Moved from_string functions and the mappings to an inl file so they don't horribly slow down the compilation on every file.

include/vulkan/vulkan_from_string.inl

@@ -15,6 +15,8 @@ namespace VULKAN_HPP_NAMESPACE
   //=== ENUMs from_string ===
   //=========================
 
+#include <vulkan/vulkan_from_string.hpp>
+
   struct EnumFromStringMap
   {
     //=== VK_VERSION_1_0 ===