Scans the PAL configure.ac looking for the version number.

    (vers, maj, min, patchlevel) = read_pal_version()

    Returns the version as a string and the major, minor
    and patchlevel version integers

def read_pal_version():
    """
    Scans the PAL configure.ac looking for the version number.

    (vers, maj, min, patchlevel) = read_pal_version()

    Returns the version as a string and the major, minor
    and patchlevel version integers

    """
    verfile = os.path.join("cextern", "pal", "configure.ac")
    verstring = "-1.-1.-1"
    for line in open(verfile):
        if line.startswith("AC_INIT"):
            # Version will be in string [nn.mm.pp]
            match = re.search(r"\[(\d+\.\d+\.\d+)\]", line)
            if match:
                verstring = match.group(1)
            break
    (major, minor, patch) = verstring.split(".")
    return (verstring, major, minor, patch)