Allow access to comment, like and menu on touchscreen devices

[marc-farre]

On touchscreen devices (mobile phones, etc.), you cannot hover an element, so you cannot access to the comment, like and menu sections of an image or a gallery

Suggestion:

On a first click/touch on an image or a gallery, show what's currently displayed when hovering:

Then with a second click/touch on the center of the image (4 arrows icon), show the fullscreen.

See also #38