Allow '+=' for archives.
Merge pull request #15 from jeromemaloberti/issue13

Allow '+=' for archives.
add "infer" as a subcommand.
add annot and bin-annot as global configuration.
add a binding to ocamlc -i for later infering.
reorganize the source to build a library for 95% of obuild.
Merge branch 'master' of github.com:vincenthz/obuild
properly report about internal libraries change in forward targets as reason for recompilation.
only rebuild the library if one of the file part of it changes.

this fix the spurious recompilation of all targets when an internal library change,
as the cmxa/cma was arbitrary rebuilt every time.
We don't need to filter syntax anymore as we source the META differently anyway.

This also fix a problem when building with a library define a syntax AND
a library at the same level.
properly add the annotation switches when needed.
turn bin annotation on.
make sure old compiler or unknown compiler don't use bin-annot. fixes #16.
fix subtitution that went haywire.
3 to 1 line.
make sure a message appears when reaching unimplemented parts of obuild.
generate META a bit better.
don't forget install.ml during the bootstrapping. fixes #18.
bump version
load findlib configuration when using obuild-simple.