Merge pull request #2 from Chris00/master

Headers fit on 80 chars.
Merge pull request #3 from Chris00/master

Improvements to the documentation.
fields are not mutable any more
add fields, depend on neturl and netdate
compilation ok after adding fields, moving to neturl and netdate
update test program; test passed
add indent option for printing; strip when reading
add Changes
ensure looking for not-prefixed attributes
remove useless let
parematrize channel_t and item_t
handle channel and item additional data in printing
fix ocamldoc comments
fix ocamldoc comments
bump version number to 2.1
handle namespaces, store them in channels, use them when writing
update Changes
install .cmxs file
remove netdate duplicated funs
remove unix dependency, add netstring instead