models. It's a better semantic and improve performance as well as
readability of the code. All the tests passes (except the remark in the
last commit).

Add of bench for @view macro.

Implementation of the lp distance for trajectories.
Add of unit tests for lp distance.

previously loaded model). The package warns when this happen.

Several benchmarks for the data structure. Now we chose the row buffer
method according to results (mainly because the trajectory access with
far way faster, but strangly not that much differences in other cases).