more ui enhancements

new in this commit:
- rounded corners everywhere! cobalt is now safe for everyone who can't handle sharp objects.
- proper banner loading. no more jumping text!
- proper banner error handling. if banner wasn't loaded, it'll simply go grey instead of disappearing.
- links are no longer italic and are instead underlined.
- collapsible lists now have corresponding emoji.
- donate button is now highlighted with magenta instead of white.
- added a list of keyboard shortcuts to about tab.
- centered old changelog loader.

package.json

@@ -1,7 +1,7 @@
 {
     "name": "cobalt",
     "description": "save what you love",
-    "version": "7.0-dev",
+    "version": "7.0-dev2",
     "author": "wukko",
     "exports": "./src/cobalt.js",
     "type": "module",