Update checkpackages function

This function doesnt really need to exit, because package loops with no
packages will simply exit the loop immediately. Also by removing the "exit" it
allows to do cool stuff like

    if checkpackages

apt-cyg

@@ -122,10 +122,12 @@ function getsetup()
 
 function checkpackages()
 {
-  if (( ! ${#packages} ))
+  if (( ${#packages} ))
   then
-    echo Nothing to do, exiting
-    exit
+    return 0
+  else
+    echo Nothing to do.
+    return 1
   fi
 }
 
@@ -220,7 +222,7 @@ case "$command" in
   ;;
 
   list)
-    if (( ${#packages} ))
+    if checkpackages
     then
       findworkspace
       for pkg in $packages
@@ -254,8 +256,8 @@ case "$command" in
   ;;
 
   show)
-    checkpackages
     findworkspace
+    checkpackages
     for pkg in $packages
     do
       echo
@@ -324,8 +326,8 @@ case "$command" in
   ;;
 
   install)
-    checkpackages
     findworkspace
+    checkpackages
     for pkg in $packages
     do