Improvements proposal for Web plugin's interface

[martinkirch]

As a long-time user of the web plug-in, I've made a few changes to its front-end. No breakthrough, but a few features turning this light page in a decent playlist :

The more or less obvious changes are :

• the controls attribute to the <audio> element - it's the simplest way to have play/pause buttons, play times, volume and navigation bar
• a Newest music link so I don't have to search added:-1w.. manually (currently it's "added last week" but maybe would be better as "added last month" ?)
• the results list on the lest is sortable, thanks to SortableJS
• individual items are removable (the X button appears when hovering each item)
• one can choose between replacing or adding search results to current items in the left bar

For a hands-on test, those changes are currently implemented in my fork, proposed for merging in PR #4335 . We're looking for feedback on such features, maybe some are not needed.