sw_concepts: replace factory example

- Draw an own stripped down variant.
- Add slide with a short explanation in front.

topics/sw_concepts/images/factory/factory-bad-case.puml

@@ -0,0 +1,26 @@
+@startuml
+
+package domain {
+
+    interface Coin
+
+    class GoldCoin implements Coin
+
+    class CopperCoin implements Coin
+
+    class SilverCoin implements Coin
+
+}
+
+package main {
+    Main --> GoldCoin : creates
+    Main --> CopperCoin : creates
+    Main --> SilverCoin : creates
+}
+
+package bank {
+    Bank --> GoldCoin : creates
+    Bank --> CopperCoin : creates
+    Bank --> SilverCoin : creates
+}
+@enduml

topics/sw_concepts/images/factory/factory-good-case.puml

@@ -0,0 +1,27 @@
+@startuml
+
+package domain {
+
+    interface Coin
+
+    class GoldCoin implements Coin
+
+    class CopperCoin implements Coin
+
+    class SilverCoin implements Coin
+
+    class CoinFactory
+
+    CoinFactory -> SilverCoin : creates
+    CoinFactory -> GoldCoin : creates
+    CoinFactory -> CopperCoin : creates
+}
+
+package main {
+    Main --> CoinFactory: uses
+}
+
+package bank {
+    Bank --> CoinFactory: uses
+}
+@enduml

topics/sw_concepts/sw_concept_slides.md

@@ -323,30 +323,25 @@ Design Patterns
 
 <https://github.com/iluwatar/java-design-patterns>
 
-Factory (method)
+Factory
 -------
 
-<https://github.com/iluwatar/java-design-patterns/blob/master/factory-method/README.md>
+* Alias: Factory Method, Simple Factory
+* Use Case:
+  * Logik für die Erstellung eines Objekts kapseln und vereinheitlichen.
+  * Wissen um konkrete Implementationen eines Interfaces zentralisieren.
 
-Factory (method) Beispiel
+von [Java Design Patterns/Factory](https://github.com/iluwatar/java-design-patterns/tree/07663ce2bdd46ca4697307068b9eb0d4c8888ead/factory)
+
+Factory Beispiel: vorher
 ------
 
-```python
-class CasiceConfigurationFactory:
-    def create(config):
-        if not config.is_casice_available():
-            return CasiceConfiguration.not_available()
-
-        if config.get_casice_host_override():
-            return CasiceConfiguration.with_host(Observable.just(config.get_casice_host_override()))
-
-        return CasiceConfiguration.with_host(
-            RetryUntilSuccess.create(
-                CasiceHostSupplier(config.get_casice_network_interface()),
-                Fibonacci.create(60).map(lambda i: 1000 * i)
-            )
-        )
-```
+![Factory Beispiel: vorher](images/factory/factory-bad-case.png){width=78%}
+
+Factory Beispiel: nachher
+------
+
+![Factory Beispiel: nachher](images/factory/factory-good-case.png)
 
 AbstractFactory
 -------