use Pmodules extended commands in modulefiles (fixing issue #3)

Tools/Firefox/modulefile

@@ -1,11 +1,11 @@
 #%Module1.0
 
-set whatis	"open source web browser"
-set url		"https://www.mozilla.org/en-US/firefox/desktop/"
-set license	" Mozilla Public License 2.0 and other"
-set maintainer	"Achim Gsell <achim.gsell@psi.ch>"
+module-whatis		"open source web browser"
+module-url		"https://www.mozilla.org/en-US/firefox/desktop/"
+module-license		" Mozilla Public License 2.0 and other"
+module-maintainer	"Achim Gsell <achim.gsell@psi.ch>"
 
-set help	"
+module-help		"
 Mozilla Firefox (known simply as Firefox) is a free and open-source web
 browser developed for Windows, OS X, and Linux, with a mobile version for
 Android, by the Mozilla Foundation and its subsidiary, the Mozilla
@@ -13,8 +13,6 @@ Corporation. Firefox uses the Gecko layout engine to render web pages, which
 implements current and anticipated web standards.
 "
 
-source		$env(PSI_LIBMODULES)
-
 if { [uname sysname] == "Darwin" } {
 	set-alias Firefox "open -n \"$PREFIX/Firefox.app\""
 }