Convert AnimARTrix usermod to library

Borrowed library definition from @netmindz's work on #4476.

platformio.ini

@@ -166,9 +166,6 @@ lib_deps =
     ; https://github.com/adafruit/Adafruit_MAX1704X @ 1.0.2
   #For MPU6050 IMU uncomment follwoing
     ;electroniccats/MPU6050 @1.0.1
-  # For -D USERMOD_ANIMARTRIX
-  # CC BY-NC 3.0 licensed effects by Stefan Petrick, include this usermod only if you accept the terms!
-    ;https://github.com/netmindz/animartrix.git#18bf17389e57c69f11bc8d04ebe1d215422c7fb7
   # SHT85
     ;robtillaart/SHT85@~0.3.3
 

usermods/usermod_v2_animartrix/library.json

@@ -0,0 +1,12 @@
+{
+  "name": "animartrix",
+  "build": {
+    "srcDir": ".",
+    "includeDir": "../../wled00",
+    "libLDFMode": "chain+",
+    "libArchive": false
+  },
+  "dependencies": {
+    "Animartrix": "https://github.com/netmindz/animartrix.git#b172586"
+  }    
+}

usermods/usermod_v2_animartrix/readme.md

@@ -6,9 +6,5 @@ CC BY-NC 3.0 licensed effects by Stefan Petrick, include this usermod only if yo
 
 ## Installation 
 
-Please uncomment the two references to ANIMartRIX in your platform.ini 
-
-lib_dep to a version of https://github.com/netmindz/animartrix.git
-and the build_flags  -D USERMOD_ANIMARTRIX
-
+Add 'animartrix' to 'custom_usermods' in your platformio_override.ini.
 

usermods/usermod_v2_animartrix/usermod_v2_animartrix.cpp

@@ -1,5 +1,3 @@
-#pragma once
-
 #include "wled.h"
 #include <ANIMartRIX.h>
 
@@ -452,5 +450,6 @@ class AnimartrixUsermod : public Usermod {
 
 };
 
-
+static AnimartrixUsermod animartrix_module("Animartrix", false);
+REGISTER_USERMOD(animartrix_module);