[tldoc] live.tex rename

[Karl Berry]

I've made what I sincerely hope are the last changes to the English
live.tex.  Notably:

- it will be named TeX Live 2007 instead of 2006, ditto the default
  directories.  I changed the examples.  A global replace will suffice,
  except for the last instances of 2006 in the history section.

- added Akira Kakuto in the list of `builders' for Windows.

- added a paragraph about the unfortunate last-minute change we were
  forced into regarding the location of .fmt files.  I hope it will be
  invisible in normal use, but it seemed prudent to mention it.  There
  is a small chance this will be reverted, but it's not likely.

New sources and output at the usual locations:
http://tug.org/svn/texlive/trunk/Master/texmf-doc/source/english/texlive-en/live.tex?view=markup
http://tug.org/svn/texlive/trunk/Master/texmf-doc/doc/english/texlive-en/live.html
http://tug.org/svn/texlive/trunk/Master/texmf-doc/doc/english/texlive-en/live.pdf

Thanks & regrets,
karl