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/clike/test.js

@@ -0,0 +1,55 @@
+// CodeMirror, copyright (c) by Marijn Haverbeke and others
+// Distributed under an MIT license: http://codemirror.net/LICENSE
+
+(function() {
+  var mode = CodeMirror.getMode({indentUnit: 2}, "text/x-c");
+  function MT(name) { test.mode(name, mode, Array.prototype.slice.call(arguments, 1)); }
+
+  MT("indent",
+     "[variable-3 void] [def foo]([variable-3 void*] [variable a], [variable-3 int] [variable b]) {",
+     "  [variable-3 int] [variable c] [operator =] [variable b] [operator +]",
+     "    [number 1];",
+     "  [keyword return] [operator *][variable a];",
+     "}");
+
+  MT("indent_switch",
+     "[keyword switch] ([variable x]) {",
+     "  [keyword case] [number 10]:",
+     "    [keyword return] [number 20];",
+     "  [keyword default]:",
+     "    [variable printf]([string \"foo %c\"], [variable x]);",
+     "}");
+
+  MT("def",
+     "[variable-3 void] [def foo]() {}",
+     "[keyword struct] [def bar]{}",
+     "[variable-3 int] [variable-3 *][def baz]() {}");
+
+  MT("def_new_line",
+     "::[variable std]::[variable SomeTerribleType][operator <][variable T][operator >]",
+     "[def SomeLongMethodNameThatDoesntFitIntoOneLine]([keyword const] [variable MyType][operator &] [variable param]) {}")
+
+  MT("double_block",
+     "[keyword for] (;;)",
+     "  [keyword for] (;;)",
+     "    [variable x][operator ++];",
+     "[keyword return];");
+
+  MT("preprocessor",
+     "[meta #define FOO 3]",
+     "[variable-3 int] [variable foo];",
+     "[meta #define BAR\\]",
+     "[meta 4]",
+     "[variable-3 unsigned] [variable-3 int] [variable bar] [operator =] [number 8];",
+     "[meta #include <baz> ][comment // comment]")
+
+
+  var mode_cpp = CodeMirror.getMode({indentUnit: 2}, "text/x-c++src");
+  function MTCPP(name) { test.mode(name, mode_cpp, Array.prototype.slice.call(arguments, 1)); }
+
+  MTCPP("cpp14_literal",
+    "[number 10'000];",
+    "[number 0b10'000];",
+    "[number 0x10'000];",
+    "[string '100000'];");
+})();