Improve suffix handling for commands.

include/internal/buffer/buffer.h

@@ -16,9 +16,13 @@ struct Buffer {
   uint64_t line = 0;
   bool modified;
   std::filesystem::path save_path = "";
+
   struct {
     uint64_t start{0};
     uint64_t end{0};
+    std::span<const uint64_t> values() const {
+      return {&start, 2};
+    }
   } prev_range;
 
   Buffer();

include/internal/commands/suffixes.h

@@ -6,7 +6,7 @@
 namespace bed::internal::commands {
 struct Suffix {
   std::string desc;
-  void (*handle)(BEd &);
+  void (*handle)(BEd &, std::span<const uint64_t>);
 
   static void register_suffixes(BEd &ctx);
 };