Added getTemplates function to MemoryLoader (#660)

* Added getTemplates function to MemoryLoader

* Change TemplateDefinition from private to public

Making the inner class TemplateDefinition public to allow external access for specific use-cases.

pebble/src/main/java/io/pebbletemplates/pebble/loader/MemoryLoader.java

@@ -37,6 +37,10 @@ public void addTemplate(String templateName, String content) {
         this.templateDefinitions.add(new TemplateDefinition(templateName, content));
     }
 
+    public List<TemplateDefinition> getTemplates() {
+        return this.templateDefinitions;
+    }
+
     @Override
     public void setSuffix(String suffix) {
     }
@@ -69,7 +73,7 @@ public boolean resourceExists(String templateName) {
         return false;
     }
 
-    private static class TemplateDefinition {
+    public static class TemplateDefinition {
         public final String templateName;
         public final String content;