Add regex search, search/replace, and buffer read-only mode functionality with help text

KKeymap.cc

@@ -33,6 +33,10 @@ KLookupKCommand(const int ascii_key, const bool ctrl, CommandId &out) -> bool
 		out = CommandId::Redo; // C-k r (redo)
 		return true;
 	}
+    if (ascii_key == '\'') {
+        out = CommandId::ToggleReadOnly; // C-k ' (toggle read-only)
+        return true;
+    }
 
 	switch (k_lower) {
 	case 'a':
@@ -59,6 +63,9 @@ KLookupKCommand(const int ascii_key, const bool ctrl, CommandId &out) -> bool
 	case 'g':
 		out = CommandId::JumpToLine;
 		return true;
+	case 'h':
+		out = CommandId::ShowHelp;
+		return true;
 	case 'j':
 		out = CommandId::JumpToMark;
 		return true;
@@ -114,7 +121,7 @@ auto
 KLookupCtrlCommand(const int ascii_key, CommandId &out) -> bool
 {
 	const int k = KLowerAscii(ascii_key);
-	switch (k) {
+ switch (k) {
 	case 'w':
 		out = CommandId::KillRegion; // C-w
 		return true;
@@ -145,9 +152,12 @@ KLookupCtrlCommand(const int ascii_key, CommandId &out) -> bool
 	case 's':
 		out = CommandId::FindStart;
 		return true;
-	case 'r':
-		out = CommandId::RegexFindStart; // C-r regex search
-		return true;
+ case 'r':
+        out = CommandId::RegexFindStart; // C-r regex search
+        return true;
+    case 't':
+        out = CommandId::RegexpReplace; // C-t regex search & replace
+        return true;
 	case 'h':
 		out = CommandId::SearchReplace; // C-h: search & replace
 		return true;