now reading timings from the meta "timings" json file

nb: json loaded as such is more picky
added actual timing file
fixed description of the timings file in the demo
fixed how the timings are formatted by the recorder (need quotes and no ',' at the end)
add 0:0 timing (slide 0 at time 0) in the timing file and the recorder
remove all data-bccue and mentions to it in the demo
player don't go to the left border anymore, such that no scrollbar appears at the end
using "display: inline-block;" on pre element to have them center