lilypond-book can hang on Windows 10

[Daniel Connors]

The python script lilypond-book.py can hang on Windows if the user's
Windows user_id is longer than 8 characters and the user's default Windows
temporary directory is in C:\Users\<user_id>.  This is because of an old,
legacy DOS filename convention.  A simple fix is to modify book_latex.py
and change line #209 to
    (handle, tmpfile) = tempfile.mkstemp('.tex', dir=".")
which will create the temporary file used by the script in the current
directory, rather than in the Windows default location.