New: Credits dialog

Added copyright information / credits dialog into the main menu.
Inspired by [tabascoeye/workadventure](7b7c695f76), requested by Chaoschemnitz

Credits dialog shows a text field. It's content should be provided by map authors
by defining a map property of type 'string' with the unique key 'license'.

Cleanup of the main menu:
- removed outline from button:active
- button paddings/margins
- removed "Create map" and "Share url"
- renamed buttons "Edit name" / "Edit skin" into "Name" / "Avatar" for
better DE support

front/dist/resources/html/gameCopyright.html

@@ -0,0 +1,89 @@
+<style>
+    *{
+        font-family: 'Open Sans', sans-serif;
+        cursor: url('/resources/logos/cursor_normal.png'), auto;
+    }
+    * a, button, input{
+        cursor: url('/resources/logos/cursor_pointer.png'), pointer;
+    }
+    #gameCopyright {
+        background: #eceeee;
+        border: 1px solid #42464b;
+        border-radius: 6px;
+        margin: 20px auto 0;
+        width: 350px;
+        height: 158px;
+    }
+    #gameCopyright h1 {
+        background-image: linear-gradient(top, #f1f3f3, #d4dae0);
+        border-bottom: 1px solid #a6abaf;
+        border-radius: 6px 6px 0 0;
+        box-sizing: border-box;
+        color: #727678;
+        display: block;
+        height: 43px;
+        padding-top: 10px;
+        margin: 0;
+        text-align: center;
+        text-shadow: 0 -1px 0 rgba(0,0,0,0.2), 0 1px 0 #fff;
+    }
+    #gameCopyright input {
+        font-size: 70%;
+        background: linear-gradient(top, #d6d7d7, #dee0e0);
+        border: 1px solid #a1a3a3;
+        border-radius: 4px;
+        box-shadow: 0 1px #fff;
+        box-sizing: border-box;
+        color: #696969;
+        height: 30px;
+        transition: box-shadow 0.3s;
+        width: 100%;
+    }
+    #gameCopyright section {
+        margin: 10px;
+    }
+    #gameCopyright section.action{
+        text-align: center;
+        margin: 0;
+    }
+    #gameCopyright button {
+        margin-top: 10px;
+        background-color: black;
+        color: white;
+        border-radius: 7px;
+        padding-bottom: 4px;
+    }
+    #gameCopyright button#gameCopyrightFormCancel {
+        background-color: #c7c7c700;
+        color: #292929;
+    }
+    #gameCopyright section a{
+        text-align: center;
+        font-size: 12px;
+        margin: 0 6px;
+        color: black;
+    }
+    #gameCopyright section h6,
+    #gameCopyright section h5{
+        margin: 1px;
+    }
+    #gameCopyright section.text-center{
+        text-align: center;
+    }
+    #gameCopyright section input#gameCopyrightLink{
+        background-color: #a1a3a3;
+    }
+</style>
+
+<form id="gameCopyright" hidden>
+    <section class="text-center">
+        <h3>Credits</h3>
+    </section>
+    <section>
+        <h6>Die Karteninhalte stehen unter folgender Lizenz:</h6>
+        <input type="text" name="copyrightLink" id="gameCopyrightLink" readonly />
+    </section>
+    <section class="action">
+        <button type="submit" id="gameCopyrightFormCancel">Close</button>
+    </section>
+</form>

front/dist/resources/html/gameMenu.html

@@ -6,11 +6,17 @@
     * a, button, select{
         cursor: url('/resources/logos/cursor_pointer.png'), pointer;
     }
+    #gameMenu {
+        padding-top: 8px;
+    }
     #gameMenu button {
         background-color: black;
         color: white;
         border-radius: 7px;
-        padding-bottom: 2px;
+        padding: 2px 8px;
+    }
+    #gameMenu button:active {
+	outline: none;
     }
     #gameMenu section {
         margin: 10px;
@@ -20,21 +26,24 @@
 <div id="gameMenu" hidden>
 
     <main>
-        <section>
+        <section hidden>
             <button id="shareButton">Share url</button>
         </section>
         <section>
-            <button id="changeNameButton">Edit name</button>
+            <button id="changeNameButton">Name</button>
         </section>
         <section>
-            <button id="changeSkinButton">Edit skin</button>
+            <button id="changeSkinButton">Avatar</button>
         </section>
         <section>
             <button id="editGameSettingsButton">Settings</button>
         </section>
-        <section>
+        <section hidden>
             <button id="sparkButton">Create map</button>
         </section>
+        <section id="copyrightSection">
+            <button id="copyrightButton">Credits</button>
+        </section>
         <section id="adminConsoleSection" hidden>
             <button id="adminConsoleButton">Admin console</button>
         </section>