This patch is inspired by Jonathan Atkin's imwheel2.patch.

It introduces a slightly different approach to mouse wheel
processing by GPM that allows to write a backward-compatible
code, and does not need recompiling all existing GPM-based
applications.

Here is the short description of changes. For a detailed
description refer to gpm.info after applying the patch:

- New members appended to Gpm_Event structure:
    w, dw - wheel displacement after previous reading, and
            current wheel position (initially set to 0)		
    pad   - reserve for future extensions
	
- New functions: Gpm_GetEventExt and Gpm_GetSnapshotExt allow
  to get the extended Gpm_Event structure, while Gpm_GetEvent
  and Gpm_GetSnapshot truncate it to the standard size for
  backward compatibility

- New event types: GPM_FWHEEL (wheel forward) and GPM_BWHEEL
  (wheel backward) provide and alternative way of wheel
  processing similar to ZAxis mapping in XFree86.

- New definition:   #define GPM_EVENT_EXT
  allows to write a backward-compatible code. 

The gpm.info has been modified to reflect the changes. After
the patch is applied and installed, type 'info gpm' for more
information regarding wheel processing.

The patch has been tested with PS/2 Intellimouse only.
                
N.B. This patch does not associate wheel motion with a keystroke,
and does not automatically provide text scrolling - 'imwheel'
package by Jonathan Atkins implements those feature, however it
may be inconsistent with the current modifications.

Michael Glickman <xsadp@yahoo.com>