use upstream mixitup
update minify to latest
update cgxp submodule
mobile slideshow: use a pool of slides

- prevents trying to load too much images at a time
- prevents ipad crash or android lag when they are lot of images (>20)
enable swipe gallery for images list pages
remove redundant title

(already present on the parent <a> tag
check that image names are shorter than 150 chars (via plupload)
Merge branch 'master' into prod