The functions optionaly exported by this module allows you to open URLs in
the user browser.
A set of known commands per OS-name is tested for presence, and the first
one found is executed. With an optional parameter, all known commands are
checked.
The "open_browser" uses the "system()" function to execute the command. If
you want more control, you can get the command with the "open_browser_cmd"
or "open_browser_cmd_all" functions and then use whatever method you want
to execute it.