Unify sysinfo plugins and add osx support

This does remove the net* commands from the
Unix version that may return at a later date
with OSX and Windows support.

This commit also makes numerious other changes
such as code cleanup, reformatting, etc.

Closes #829

po/POTFILES.in

@@ -43,3 +43,4 @@ src/fe-gtk/textgui.c
 src/fe-gtk/urlgrab.c
 src/fe-gtk/userlistgui.c
 src/fe-text/fe-text.c
+plugins/sysinfo/sysinfo.c