Fastq: factor out parse functions

Currently were embedded within string_to_item function. Also, I defined
the functions as exception-ful.
Fastq Lwt module added

Beginnings of a biocaml lwt library as requested in #125.
OMakeroot: minor grammar fix
OMakeroot: use OCAMLC_EXISTS to set BYTE_ENABLED
OMakeroot: replace some hardcoded values with variables

Helps #121.
OMakeroot: delete LIB_VERSION

It was redundant to VERSION. Helps #121.
OMakeroot: remove DEPENDENCIES and rename PACKAGES

DEPENDENCIES was not needed and incorrectly used in META file. PACKAGES
really should be called LIB_PACKAGES for consistency with all other
FOO_PACKAGES variables. Helps #121.
OMakeroot: correctly define and use FOO_PACKAGES variables

Helps #121.