Remove useless test
Adds set_value function for spot lights
Adds shallowcopy for the inheritance

shallowcopy it is a first level of copy. Don't copy in deeper
Adds implementation of getter and setter of priv table

These function are used to catch the used of key 'value'. Every time
you set or write the priv["value"] these function are called. That means
you can change the behavior of the generic attribute 'value'.
bug fix : is_change and ack are now from priv
Adds delinearize function
Applies the behavior of 'value' attribute to parled and spot
Adds lspot class for spot that need to be linearize
Adds the total_time and the step has parameter for tasks
Changes tests
Adds backtrace for debug
Adds generic function Wave and Flash
Simplifies Spectre function
Increase debug information when there is a syntax error