Improved online help and chm file for NirCmd

NirCmd has 2 new improvements in the commands reference:

1. The .chm file now contains a list of all commands in the contents, allows you to easily jump to the right NirCmd command.
   
   
   
   
2. New online help of NirCmd is available in http://nircmd.nirsoft.net
   You can easily open the right command in this online help, simply by using help command of NirCmd, for example:
   NirCmd.exe help setvolume
   
   the above command will open your default Web browser in http://nircmd.nirsoft.net/setvolume.html