Get_dwgpreview unpack the preview picture of a DWG file.

The supported versions of DWG are R_13,R_14, R_2000.
The versions R_2004 and R_2007 of DWG are in alpha state and unstable and buggy.


DWG is a file format created in the 70's for the emerging CAD applications.
Currently it is the native file format of AutoCAD, a proprietary CAD program 
developed by AutoDesk.

PERMISSION  UID  GID    PACKED    SIZE  RATIO METHOD CRC     STAMP     NAME
---------- ----------- ------- ------- ------ ---------- ------------ ----------
[unknown]                73618  203716  36.1% -lh5- 585d Nov 28 05:55 get_dwgpreview/get_dwgpreview
[unknown]                  341     623  54.7% -lh5- 6b09 Nov 28 06:02 get_dwgpreview/get_dwgpreview.readme
[unknown]                 4021   22027  18.3% -lh5- ea58 Feb  5  2013 get_dwgpreview/sample.dwg
---------- ----------- ------- ------- ------ ---------- ------------ ----------
 Total         3 files   77980  226366  34.4%            Nov 28 21:41