Support for HWg-PWR device added

I have added improved support for these devices: http://www.hw-group.com/products/HWg-PWR/hwg-pwr25_M-bus_gateway_en.html

As I don't really have programming skills I tried to adapt the configuration of the HWG-STE device, as it is form the same manufacturer.
Therefore I modified the existing hwg-pwr entry in os.in.php to:

os = "hwg-pwr";
$config['os'][$os]['text'] = "HWg-PWR";
$config['os'][$os]['type'] = "environment";
$config['os'][$os]['snmp']['nobulk'] = 1;
$config['os'][$os]['vendor'] = "HW Group";
$config['os'][$os]['icon'] = "hwggroup";
$config['os'][$os]['sysObjectID'][] = ".1.3.6.1.4.1.21796.4.6";
$config['os'][$os]['mibs'][] = "HWG-PWR-MIB";

I also added a new icon, see attachment.
Enclosed you will also find the MIB file HWG-PWR-MIB I have placed to /mibs/hwgroup.

I added another sensor type called energy to display the kWh:
/includes/definitions/sensors.inc.php
==> $config['sensor_types']['energy'] = array( 'symbol' => 'kWh', 'text' => 'kiloWatthours','icon' => 'oicon-power');

Enclosed I am also sending you the newly created files:
/html/includes/graphs/sensor/energy.inc.php
/includes/discovery/sensors/hwg-pwr-mib.inc.php

Everything works fine for me...