Merge c68a3ee136 into 5fae7a6249

[__JETBRAINS_IDE__](https://blog.jetbrains.com/clion/2017/02/clion-2017-1-eap-debugger-fixes-ide-macros-and-new-cmake/) is defined within Jetbrains editors like CLion and Rider. This is only defined inside the IDE, and does not affect builds, so we can use it to enable CLAY_IMPLEMENTATION to improve debugging & intellisense in this environment. I'm not sure if other IDEs have similar macros, but I figured we could start with this one

clay.h

@@ -14,6 +14,11 @@
 #include <stdbool.h>
 #include <stddef.h>
 
+#ifdef __JETBRAINS_IDE__
+// Help jetbrains IDEs like CLion and Rider with intellisense & debugging
+#define CLAY_IMPLEMENTATION
+#endif
+
 // -----------------------------------------
 // HEADER DECLARATIONS ---------------------
 // -----------------------------------------