First commit. Add node to a list, destroy a list.
Function to run callbacks for all elements in the linked list.
Better encapsulation, simpler API.
List copy.

makefile correction (clean was wrong), and set optimizing.
Sublist copy. More error checks.
Cross two lists at given positions.

Added a number of const to avoid accidental modifications.
New test method that reads elements of lists into an array, instead of
the more cumbersome cumulative sum.

test in makefile builds and runs the test in one command.
Removed warning for unused functions, since help functions such as
display() are often not used.
New helper functions in test, smaller and better test cases.
Add a function to get that data at a given position in a list.
Merge branch 'master' of https://github.com/fleutot/linkedlist