- removed enum STATE_TYPE because we solved this better
- removed tape_action.h, tape_action.c and moved this functionality to
  tape_actions completely
- replaced data member of tape_actions with three arrays:
    vec_read - array of uintptr_t pointers (read vector)
    vec_write - array of uintptr_t pointers (write vector)
    vec_dirs - array of SHIFT_DIR enums (direction vector
- removed priv member from tape
- added safety checks in state.c tape_cell_list.c, tape_cell.c,
  tape_actions.c, tm.c, edge_list.c, state_list.c (almost every .c-file)
  tape.c, tapes.c
- removed functions which used edge_default like tapes_apply_actions_default...
- removed alphabet