Added ll_select() interface and implementation
Added avl_select() interface and file for impl.
Added implementation for avl_select() including helper func
Added interface for ht_select() and impl file
Add: Implementation for ht_select()
Added impl. of insert helper function
Add typedef for selection functions
Add avl_select.c and ht_select.c to source file list
Redefine ll_select()
Redefine avl_select()
Redefine ht_select()
Redefine r_set_select()