*************************************************************************
* Author    : Tiago Dionizio <tiago.dionizio@gmail.com>                 *
* Library   : lgzip - a gzip file access binding for Lua 5              *
*             based on liolib.c from Lua 5.0 library                    *
*                                                                       *
* Permission is hereby granted, free of charge, to any person obtaining *
* a copy of this software and associated documentation files (the       *
* "Software"), to deal in the Software without restriction, including   *
* without limitation the rights to use, copy, modify, merge, publish,   *
* distribute, sublicense, and/or sell copies of the Software, and to    *
* permit persons to whom the Software is furnished to do so, subject to *
* the following conditions:                                             *
*                                                                       *
* The above copyright notice and this permission notice shall be        *
* included in all copies or substantial portions of the Software.       *
*                                                                       *
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       *
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    *
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*
* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  *
* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  *
* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     *
* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                *
*************************************************************************

To use this library you need zlib library.
You can get it from http://www.gzip.org/zlib/


GZIP file handling on top of the zlib interface.

TODO:
	- detect plain text files
	- proper testing
	- improve implementation?
	- check gzopen flags for consistency (ex: strategy flag)

Loading the library:

    [local] gzip = require 'gzip'

gzip.open(filename [, mode])

    Opens a file name using "gzopen". Behaviour is identical to the description
    given in the zlib library. If mode is not given a default mode "r" will be
    used. Mode is the same as interpreted by gzopen function, ie, it can
    include special modes such as characters 1 to 9 that will be treated as the
    compression level when opening a file for writing.

    It returns a new file handle, or, in case of errors, nil plus an error
    message

gzip.lines(filename)

    Same behaviour as io.lines in the io standard library provided by lua
    with the aditional feature of working with gzip files. If a normal text
    file is read it will read it normaly.

gzip.close(file)

    Same as file:close, use file:close instead.

file:flush()

    This function takes no parameters and flushes all output to working file.
    The same as calling 'gzflush(file, Z_FINISH)' so writing to the file will
    most likely not work as expected. This is subject to change in the future
    if there is a strong reason for it to happen.

file:read(format1, ...)
    Reads the file file, according to the given formats, which specify what
    to read. For each format, the function returns a string with the characters
    read, or nil if it cannot read data with the specified format. When called
    without formats, it uses a default format that reads the entire next line
    (see below).

    The available formats are

        "*a"   reads the whole file, starting at the current position. On end of
               file, it returns the empty string.
        "*l"   reads the next line (skipping the end of line), returning nil on
               end of file. This is the default format.
        number reads a string with up to that number of characters, returning
               nil on end of file. If number is zero, it reads nothing and
               returns an empty string, or nil on end of file.

    Unlike io.read, the "*n" format will not be available.


file:lines()

    Returns an iterator function that, each time it is called, returns a new
    line from the file. Therefore, the construction

       for line in file:lines() do ... end

    will iterate over all lines of the file.

file:write(value1, ...)

    Writes the value of each of its arguments to the filehandle file. The
    arguments must be strings or numbers. To write other values, use tostring
    or string.format before write

file:close()

    Closes the file.