Implement 'hide all sprites' and 'user id' blocks

src/blocks/scratch3_looks.js

@@ -244,6 +244,7 @@ class Scratch3LooksBlocks {
             looks_thinkforsecs: this.thinkforsecs,
             looks_show: this.show,
             looks_hide: this.hide,
+            looks_hideallsprites: this.doNothing,
             looks_switchcostumeto: this.switchCostume,
             looks_switchbackdropto: this.switchBackdrop,
             looks_switchbackdroptoandwait: this.switchBackdropAndWait,
@@ -479,6 +480,8 @@ class Scratch3LooksBlocks {
         // Else return name
         return util.target.getCostumes()[util.target.currentCostume].name;
     }
+
+    doNothing() {}
 }
 
 module.exports = Scratch3LooksBlocks;

src/blocks/scratch3_sensing.js

@@ -66,7 +66,8 @@ class Scratch3SensingBlocks {
             sensing_dayssince2000: this.daysSince2000,
             sensing_loudness: this.getLoudness,
             sensing_askandwait: this.askAndWait,
-            sensing_answer: this.getAnswer
+            sensing_answer: this.getAnswer,
+            sensing_userid: this.doNothing
         };
     }
 
@@ -293,6 +294,8 @@ class Scratch3SensingBlocks {
         // Otherwise, 0
         return 0;
     }
+
+    doNothing() {}
 }
 
 module.exports = Scratch3SensingBlocks;

src/serialization/sb2_specmap.js

@@ -266,6 +266,11 @@ const specMap = {
         argMap: [
         ]
     },
+    'hideAll': {
+        opcode: 'looks_hideallsprites',
+        argMap: [
+        ]
+    },
     'lookLike:': {
         opcode: 'looks_switchcostumeto',
         argMap: [
@@ -1043,6 +1048,11 @@ const specMap = {
         argMap: [
         ]
     },
+    'getUserId': {
+        opcode: 'sensing_userid',
+        argMap: [
+        ]
+    },
     '+': {
         opcode: 'operator_add',
         argMap: [