Moved vendored js/css into public/vendor and documented sources (#1484) (#2241)

* Cleaning up public/ and documenting js/css libs.

This commit mostly addresses #1484 by moving vendor'ed plugins into a
vendor/ directory and documenting their upstream source and license in
vendor/librejs.html.

This also proves gitea is using only open source js/css libraries which
helps toward reaching #1524.

* Removing unused css file.

The version of this file in use is located at:
  vendor/plugins/highlight/github.css

* Cleaned up librejs.html and added javascript header

A SafeJS function was added to templates/helper.go to allow keeping
comments inside of javascript.

A javascript comment was added in the header of templates/base/head.tmpl
to mark all non-inline source as free.

The librejs.html file was updated to meet the current librejs spec. I
have now verified that the librejs plugin detects most of the scripts
included in gitea and suspect the non-free detections are the result of
a bug in the plugin. I believe this commit is enough to meet the C0.0
requirement of #1534.

* Updating SafeJS function per lint suggestion

* Added VERSIONS file, per request

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

@@ -0,0 +1,69 @@
+// CodeMirror, copyright (c) by Marijn Haverbeke and others
+// Distributed under an MIT license: http://codemirror.net/LICENSE
+
+(function() {
+  var mode = CodeMirror.getMode({indentUnit: 2}, "jsx")
+  function MT(name) { test.mode(name, mode, Array.prototype.slice.call(arguments, 1)) }
+
+  MT("selfclose",
+     "[keyword var] [def x] [operator =] [bracket&tag <] [tag foo] [bracket&tag />] [operator +] [number 1];")
+
+  MT("openclose",
+     "([bracket&tag <][tag foo][bracket&tag >]hello [atom &amp;][bracket&tag </][tag foo][bracket&tag >][operator ++])")
+
+  MT("attr",
+     "([bracket&tag <][tag foo] [attribute abc]=[string 'value'][bracket&tag >]hello [atom &amp;][bracket&tag </][tag foo][bracket&tag >][operator ++])")
+
+  MT("braced_attr",
+     "([bracket&tag <][tag foo] [attribute abc]={[number 10]}[bracket&tag >]hello [atom &amp;][bracket&tag </][tag foo][bracket&tag >][operator ++])")
+
+  MT("braced_text",
+     "([bracket&tag <][tag foo][bracket&tag >]hello {[number 10]} [atom &amp;][bracket&tag </][tag foo][bracket&tag >][operator ++])")
+
+  MT("nested_tag",
+     "([bracket&tag <][tag foo][bracket&tag ><][tag bar][bracket&tag ></][tag bar][bracket&tag ></][tag foo][bracket&tag >][operator ++])")
+
+  MT("nested_jsx",
+     "[keyword return] (",
+     "  [bracket&tag <][tag foo][bracket&tag >]",
+     "    say {[number 1] [operator +] [bracket&tag <][tag bar] [attribute attr]={[number 10]}[bracket&tag />]}!",
+     "  [bracket&tag </][tag foo][bracket&tag >][operator ++]",
+     ")")
+
+  MT("preserve_js_context",
+     "[variable x] [operator =] [string-2 `quasi${][bracket&tag <][tag foo][bracket&tag />][string-2 }quoted`]")
+
+  MT("line_comment",
+     "([bracket&tag <][tag foo] [comment // hello]",
+     "   [bracket&tag ></][tag foo][bracket&tag >][operator ++])")
+
+  MT("line_comment_not_in_tag",
+     "([bracket&tag <][tag foo][bracket&tag >] // hello",
+     "  [bracket&tag </][tag foo][bracket&tag >][operator ++])")
+
+  MT("block_comment",
+     "([bracket&tag <][tag foo] [comment /* hello]",
+     "[comment    line 2]",
+     "[comment    line 3 */] [bracket&tag ></][tag foo][bracket&tag >][operator ++])")
+
+  MT("block_comment_not_in_tag",
+     "([bracket&tag <][tag foo][bracket&tag >]/* hello",
+     "    line 2",
+     "    line 3 */ [bracket&tag </][tag foo][bracket&tag >][operator ++])")
+
+  MT("missing_attr",
+     "([bracket&tag <][tag foo] [attribute selected][bracket&tag />][operator ++])")
+
+  MT("indent_js",
+     "([bracket&tag <][tag foo][bracket&tag >]",
+     "    [bracket&tag <][tag bar] [attribute baz]={[keyword function]() {",
+     "        [keyword return] [number 10]",
+     "      }}[bracket&tag />]",
+     "  [bracket&tag </][tag foo][bracket&tag >])")
+
+  MT("spread",
+     "([bracket&tag <][tag foo] [attribute bar]={[meta ...][variable baz] [operator /][number 2]}[bracket&tag />])")
+
+  MT("tag_attribute",
+     "([bracket&tag <][tag foo] [attribute bar]=[bracket&tag <][tag foo][bracket&tag />/>][operator ++])")
+})()