Minor internal code tweaks

* mark all eligible classes Final
* new TableIndex strong type
* buildfixes for HAVE_DEBUGSPEW()
* overridden virtual destructors tagged as such

1 files changed, 1 insertions, 1 deletions

diff --git a/src/keeper.cpp b/src/keeper.cpp
index 2d9d800..43f3125 100644
--- a/src/keeper.cpp
+++ b/src/keeper.cpp
@@ -60,7 +60,7 @@ namespace {
 // #################################################################################################
 
 // the full userdata associated to a given Linda key to store its contents
-class KeyUD
+class KeyUD final
 {
     private:
     static constexpr UserValueIndex kContentsTableIndex{ 1 };