Move 3rd party js/css into public/vendor and document sources (#2383)

This commit cherry picks the following commits (master -> v1.2):
  a915a09
  874f9be
  233bbcf

Ref: https://github.com/go-gitea/gitea/issues/1484
Signed-off-by: Michael Lustfield <michael@lustfield.net>

public/vendor/plugins/codemirror/mode/python/test.js

@@ -0,0 +1,30 @@
+// CodeMirror, copyright (c) by Marijn Haverbeke and others
+// Distributed under an MIT license: http://codemirror.net/LICENSE
+
+(function() {
+  var mode = CodeMirror.getMode({indentUnit: 4},
+              {name: "python",
+               version: 3,
+               singleLineStringErrors: false});
+  function MT(name) { test.mode(name, mode, Array.prototype.slice.call(arguments, 1)); }
+
+  // Error, because "foobarhello" is neither a known type or property, but
+  // property was expected (after "and"), and it should be in parentheses.
+  MT("decoratorStartOfLine",
+     "[meta @dec]",
+     "[keyword def] [def function]():",
+     "    [keyword pass]");
+
+  MT("decoratorIndented",
+     "[keyword class] [def Foo]:",
+     "    [meta @dec]",
+     "    [keyword def] [def function]():",
+     "        [keyword pass]");
+
+  MT("matmulWithSpace:", "[variable a] [operator @] [variable b]");
+  MT("matmulWithoutSpace:", "[variable a][operator @][variable b]");
+  MT("matmulSpaceBefore:", "[variable a] [operator @][variable b]");
+
+  MT("fValidStringPrefix", "[string f'this is a {formatted} string']");
+  MT("uValidStringPrefix", "[string u'this is an unicode string']");
+})();