Spring Cleaning, and  Load speedup

0) prompt '*' strore fix + tab remove tooltip
tab was not cancelling tooltip bringing to cases where you could have
tooltip andcompleter open.

Do not store '*' when serializing cells.


get rid of most slowdown at notebook loading.
1) Do not setOption('mode',new_mode) on CM if new and old mode are the
   same. It triggert **a lot** of calculation of bounding box in the
   end.

2) Do **not** select cell when loading the notebook it triggers
   **a lot** of CM even that check visible things and so on and so
   forth. So add a option to add_cell_at_index not to select it

3) jQuery $.attr has some magics, but has a slight overhead on
   real native ELEM.setAttribute DOM method. Seem slight improvement
   when loads of PNGs on one page