Specify library version & versioning rules in headers

Author: wjakob

include/tsl/robin_growth_policy.h

@@ -35,6 +35,13 @@
 #include <ratio>
 #include <stdexcept>
 
+// A change of the major version indicates an API and/or ABI break (change of in-memory layout of the data structure)
+#define TSL_RH_VERSION_MAJOR 1
+// A change of the minor version indicates the addition of a feature without impact on the API/ABI
+#define TSL_RH_VERSION_MINOR 2
+// A change of the patch version indicates a bugfix without additional functionality
+#define TSL_RH_VERSION_PATCH 1
+
 #ifdef TSL_DEBUG
 #define tsl_rh_assert(expr) assert(expr)
 #else