(insert_start_shifting_state): this.
(insert_eof_shifting_state, insert_accepting_state): New.
(augment_automaton): Adjust.
Better locality of the variables.
When looking if the start_symbol is shifted from the initial
state, using `while (... symbol != start_symbol ...)' sounds
better than `while (... symbol < start_symbol ...)': If fail
to see how the order between symbols could be relevant!