This bumping of version is insignificant.  I just find it notable that
I seem to finally obtain a version without trivial bugs.  Hooray!

The chain-rule machine needs a place-holder node at the beginning.
But afterwards that node is pure annoyance and disturbs the
functioning of the machine.  Consequently I removed that node whenever
the right time comes.

This seems to fix some other bugs.  It is reasonable: the presence of
that bogus node is just noise to the machine and error-prone.

* chain/src/atom/default.rs (print_virtual): Previously printing
  virtual nodes is done inside the function `print_nfa`; now this is
  decoupled and thus more flexible.

* chain/src/item/genins.rs: The absolute path is too long and
  unnecessary.

* grammar/src/label.rs (set_end_option): This function replaces the
  old function `open_end`, as this new function is more general than
  the old one, and there is no specific situation where we only need
  to open the end of a node without the need to close the node in an
  `if` statement.

* chain/src/item/default/splone.rs: Previouslt the function
  `split_node` used to split the parents of splitted nodes by an ugly
  logic.  Now that is moved into a dedicated function, which properly
  handles the splitting of parents, including the case when the new
  node is open whereas the old node is closed, in which situation we
  ought to put the new node under the opened node only, as a closed
  node cannot contain an open node as a child by definition.

Huh.

* graph/src/lib.rs: Add a plan to reduce the number of
  bounds-checking.  Hopefully this makes the package more efficient.

* chain/src/atom/default.rs: Making this function public means I do
  not have to worry about it being unused.