Revert "[focuschain/task switcher] Remove special handling for minimized windows"

This reverts commit cc862fa6.

It turns out that some people like this behavior and we've received
various user complaints about it.

abstract_client.cpp

@@ -703,6 +703,7 @@ void AbstractClient::minimize(bool avoid_animation)
     doMinimize();
 
     updateWindowRules(Rules::Minimize);
+    FocusChain::self()->update(this, FocusChain::MakeFirstMinimized);
     // TODO: merge signal with s_minimized
     addWorkspaceRepaint(visibleRect());
     emit clientMinimized(this, !avoid_animation);

focuschain.cpp

@@ -227,7 +227,17 @@ AbstractClient *FocusChain::nextForDesktop(AbstractClient *reference, uint deskt
 void FocusChain::makeFirstInChain(AbstractClient *client, Chain &chain)
 {
     chain.removeAll(client);
-    chain.append(client);
+    if (client->isMinimized()) { // add it before the first minimized ...
+        for (int i = chain.count()-1; i >= 0; --i) {
+            if (chain.at(i)->isMinimized()) {
+                chain.insert(i+1, client);
+                return;
+            }
+        }
+        chain.prepend(client); // ... or at end of chain
+    } else {
+        chain.append(client);
+    }
 }
 
 void FocusChain::makeLastInChain(AbstractClient *client, Chain &chain)

focuschain.h

@@ -41,7 +41,8 @@ public:
     enum Change {
         MakeFirst,
         MakeLast,
-        Update
+        Update,
+        MakeFirstMinimized = MakeFirst
     };
     ~FocusChain() override;
     /**