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/rust/test.js

@@ -0,0 +1,39 @@
+// CodeMirror, copyright (c) by Marijn Haverbeke and others
+// Distributed under an MIT license: http://codemirror.net/LICENSE
+
+(function() {
+  var mode = CodeMirror.getMode({indentUnit: 4}, "rust");
+  function MT(name) {test.mode(name, mode, Array.prototype.slice.call(arguments, 1));}
+
+  MT('integer_test',
+     '[number 123i32]',
+     '[number 123u32]',
+     '[number 123_u32]',
+     '[number 0xff_u8]',
+     '[number 0o70_i16]',
+     '[number 0b1111_1111_1001_0000_i32]',
+     '[number 0usize]');
+
+  MT('float_test',
+     '[number 123.0f64]',
+     '[number 0.1f64]',
+     '[number 0.1f32]',
+     '[number 12E+99_f64]');
+
+  MT('string-literals-test',
+     '[string "foo"]',
+     '[string r"foo"]',
+     '[string "\\"foo\\""]',
+     '[string r#""foo""#]',
+     '[string "foo #\\"# bar"]',
+
+     '[string b"foo"]',
+     '[string br"foo"]',
+     '[string b"\\"foo\\""]',
+     '[string br#""foo""#]',
+     '[string br##"foo #" bar"##]',
+
+     "[string-2 'h']",
+     "[string-2 b'h']");
+
+})();