Manual merge: big jQuery optimisation of init_posts()

https://github.com/Alkarex/FreshRSS/pull/18
Manual merge: jQuery updated from version 1.5.2 to 1.10.2

https://github.com/Alkarex/FreshRSS/commit/f897d64f1c82d3903ae3d70e4935360c701f6329