Makes mod editing only send changed data (#286)

* Add getDifferences lib

* Only send mod diff to backend for changes

* Disable fields when lacking permissions

assets/styles/global.scss

@@ -234,7 +234,7 @@ textarea {
   border: 2px solid transparent;
 
   &:focus,
-  &:hover {
+  &:hover:not([disabled]) {
     background: var(--color-button-bg-hover);
     color: var(--color-text);
     outline: none;
@@ -252,6 +252,13 @@ textarea {
   &::placeholder {
     color: var(--color-color-text);
   }
+
+  &:disabled,
+  &[disabled] {
+    opacity: 0.6;
+    pointer-events: none;
+    cursor: not-allowed;
+  }
 }
 
 .ea-content {