update .gitignore to ignore src/runtime except for certain files

.gitignore

@@ -28,6 +28,14 @@ scratch*
 
 /test*
 
+#do not ignore src/runtime folder (needed to re-include what we do want from within)
+!/src/runtime
+#ignore files and sub dirs in src/runtime
+/src/runtime/*
+#but do not ignore specific files
+!/src/runtime/Readme.md
+!/src/runtime/tclkit.ico
+!/src/runtime/mapvfs.config
 
 #Built tclkits (if any)
 punk*.exe