Make almost all of MacroButtonProperties fields non-null

Most of the fields were either close to being non-nullable, or had getters that enforced non-nullability for callers. As
a result, most of them were readily made truly non-nullable, which enabled us to avoid the need for `null` checks
outside of setters and `readResolve()`.

`StringBuilder` is now used locally instead of `StringBuffer` in `modifySortString()` as it is lighterweight and there
is no multithreading concerns.

src/main/java/net/rptools/maptool/client/functions/MacroFunctions.java

@@ -173,7 +173,7 @@ public Object getMacroButtonProps(Token token, int index, String delim) throws P
       props.addProperty("playerEditable", mbp.getAllowPlayerEdits());
       props.addProperty("command", mbp.getCommand());
       props.addProperty("maxWidth", mbp.getMaxWidth());
-      props.addProperty("tooltip", mbp.getToolTip() == null ? "" : mbp.getToolTip());
+      props.addProperty("tooltip", mbp.getToolTip());
       props.addProperty("applyToSelected", mbp.getApplyToTokens());
 
       JsonArray compare = new JsonArray();
@@ -223,7 +223,7 @@ public Object getMacroButtonProps(Token token, int index, String delim) throws P
       sb.append("minWidth=").append(mbp.getMinWidth()).append(delim);
       sb.append("playerEditable=").append(mbp.getAllowPlayerEdits()).append(delim);
       sb.append("maxWidth=").append(mbp.getMaxWidth()).append(delim);
-      sb.append("tooltip=").append(mbp.getToolTip() == null ? "" : mbp.getToolTip()).append(delim);
+      sb.append("tooltip=").append(mbp.getToolTip()).append(delim);
       sb.append("applyToSelected=").append(mbp.getApplyToTokens()).append(delim);
       return sb.toString();
     }
@@ -419,8 +419,7 @@ private String getMacroCommand(int index, Token token) throws ParserException {
       throw new ParserException(
           I18N.getText(KEY_OUT_OF_RANGE, "getMacroCommand", index, token.getName()));
     }
-    String cmd = mbp.getCommand();
-    return cmd != null ? cmd : "";
+    return mbp.getCommand();
   }
 
   /**

src/main/java/net/rptools/maptool/client/ui/TokenPopupMenu.java

@@ -151,10 +151,7 @@ protected JMenu createMacroMenu() {
     Map<String, JMenu> groups = new TreeMap<String, JMenu>();
     for (MacroButtonProperties macro : macroList) {
       group = macro.getGroup();
-      group =
-          (group == null || group.isEmpty()
-              ? " General"
-              : group); // leading space makes it come first
+      group = (group.isEmpty() ? " General" : group); // leading space makes it come first
       JMenu submenu = groups.get(group);
       if (submenu == null) {
         submenu = new JMenu(group);

src/main/java/net/rptools/maptool/client/ui/macrobuttons/buttongroups/AbstractButtonGroup.java

@@ -155,7 +155,6 @@ public List<MacroButtonProperties> getPropertiesList() {
   }
 
   public void setPropertiesList(List<MacroButtonProperties> propertiesList) {
-    MacroButtonProperties.fixOldMacroSetCompare(propertiesList);
     this.propertiesList = propertiesList;
   }
 

src/main/java/net/rptools/maptool/client/ui/macrobuttons/buttons/MacroButton.java

@@ -82,7 +82,6 @@ public MacroButton(MacroButtonProperties properties, ButtonGroup buttonGroup, To
     }
     this.properties.setTokenId(this.tokenId);
     this.properties.setSaveLocation(this.panelClass);
-    this.properties.setButton(this);
     // we have to call setColor() and setText() here since properties only hold "dumb" data.
     setColor(properties.getColorKey());
     setText(getButtonText());

src/main/java/net/rptools/maptool/client/ui/macrobuttons/dialog/MacroButtonDialog.java

@@ -308,7 +308,7 @@ public void show(MacroButton button) {
 
     if (properties != null) {
       oldHashCode = properties.hashCodeForComparison();
-      Boolean playerCanEdit = !MapTool.getPlayer().isGM() && properties.getAllowPlayerEdits();
+      boolean playerCanEdit = !MapTool.getPlayer().isGM() && properties.getAllowPlayerEdits();
       boolean onGlobalPanel = properties.getSaveLocation().equals("Global");
       boolean allowEdits = onGlobalPanel || MapTool.getPlayer().isGM() || playerCanEdit;
       boolean isCommonMacro =