Added common.h for set debug macro
Add debug prints for r_set_new()
Add debug prints for r_set_destroy()
Add debug print for r_set_insert()
Add debug print for r_set_remove()
Add debug print for r_set_contains()
Add debug print for r_set_cardinality()
Merge pull request #255 from matthiasbeyer/add-debug_printing_set

Add debug printing for set type