feat #575 Improve documentation for the API viewer

Fix some typos and correct links to bean descriptions

Close #575
fix #589 Considering scrollbars width on Mac

When on mac the method aria.templates.Layout.getScrollbarsWidth() returns zero, due to the fact that on mac the scrollbars are managed differently. So in this case we add 17px in order to consider them and to avoid to crop some content.
feat #500 utils.String.dashedToCamel|camelToDashed
fix #499 conform standards regarding dataset in Html.buildAttributeList

Added check for invalid keys passed to `dataset` in
utils.Html.buildAttributeList.

So far it only logs warning, to be switched in backward-incompatible
release.

Close #500.