Fix ESLint errors, bugs, and add gravity export

- Fix missing return in childRegistrationUtils.registerChild()
- Fix assertionUtils: assertNoNaN uses this.assertNoNaN
- Fix logger: nameModule uses this.nameModule
- Fix assetUtils: convert ESM to CommonJS
- Fix childRegistrationUtils_DEPRECATED: desc -> softwareType
- Add gravity export to index.js for rotatingMachine
- Fix ESLint errors across 18 files (no-undef, no-case-declarations,
  no-mixed-spaces-and-tabs, parsing errors)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/convert/index.js

@@ -127,7 +127,7 @@ Converter.prototype.toBest = function(options) {
   if(!this.origin)
     throw new Error('.toBest must be called after .from');
 
-  var options = Object.assign({
+  options = Object.assign({
     exclude: [],
     cutOffNumber: 1,
   }, options)
@@ -268,22 +268,22 @@ Converter.prototype.throwUnsupportedUnitError = function (what) {
 Converter.prototype.possibilities = function (measure) {
   var possibilities = [];
   if(!this.origin && !measure) {
-	  each(keys(measures), function (measure){
-		  each(measures[measure], function (units, system) {
-		    if(system == '_anchors')
-		      return false;
+    each(keys(measures), function (measure){
+      each(measures[measure], function (units, system) {
+        if(system == '_anchors')
+          return false;
 
-		    possibilities = possibilities.concat(keys(units));
-		  });
-	  });
+        possibilities = possibilities.concat(keys(units));
+      });
+    });
   } else {
-	  measure = measure || this.origin.measure;
-	  each(measures[measure], function (units, system) {
-	    if(system == '_anchors')
-	      return false;
+    measure = measure || this.origin.measure;
+    each(measures[measure], function (units, system) {
+      if(system == '_anchors')
+        return false;
 
-	    possibilities = possibilities.concat(keys(units));
-	  });
+      possibilities = possibilities.concat(keys(units));
+    });
   }
 
   return possibilities;