Use select instead of poll
Adds spots ligth type
bug fix: wrong pop on lua stack
changes polling server method
Change pow function to get a correct behavior
bug fix: change select outside the block
changes test.lua file
removes compilation warning
New algorithm for triangle - Not perfect yet -
Adds sift signal
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