Set some DOM transformation to fix some of the accessibility issues

See #337 for the complete rationale by @ndarilek -- thank you :)

Closes #338

client/lib/accessibility.js

@@ -0,0 +1,41 @@
+// In this file we define a set of DOM transformations that are specifically
+// intended for blind screen readers.
+//
+// See https://github.com/wekan/wekan/issues/337 for the general accessibility
+// considerations.
+
+// Without an href, links are non-keyboard-focusable and are not presented on
+// blind screen readers. We default to the empty anchor `#` href.
+function enforceHref(attributes) {
+  if (! _.has(attributes, 'href')) {
+    attributes.href = '#';
+  }
+  return attributes;
+}
+
+// `title` is inconsistently used on the web, and is thus inconsistently
+// presented by screen readers. `aria-label`, on the other hand, is specific to
+// accessibility and is presented in ways that title shouldn't be.
+function copyTitleInAriaLabel(attributes) {
+  if (! _.has(attributes, 'aria-label') && _.has(attributes, 'title')) {
+    attributes['aria-label'] = attributes.title;
+  }
+  return attributes;
+}
+
+// XXX Our implementation relies on overwriting Blaze virtual DOM functions,
+// which is a little bit hacky -- but still reasonable with our ES6 usage. If we
+// end up switching to React we will probably create lower level small
+// components to handle that without overwriting any build-in function.
+const {
+  A: superA,
+  I: superI,
+} = HTML;
+
+HTML.A = (attributes, ...others) => {
+  return superA(copyTitleInAriaLabel(enforceHref(attributes)), ...others);
+}
+
+HTML.I = (attributes, ...others) => {
+  return superI(copyTitleInAriaLabel(attributes), ...others);
+}