Minor tweaks to Book I

I've just uploaded new versions of the poem. If I've managed these correctly, they should be almost identical to the previous finished form.

I wanted to make some further small improvements to Book I, which has always displayed some, so to speak, technical debt as the first part of the poem written. Nothing has changed plotwise, but a few lines have grown more metrical and I've found some choices of words which hit more true. Please let me know if you discover any errors or problems!