feat(lib): allow shortcuts to use variables

Author: abgox

lib/shortcuts.ps1

@@ -2,7 +2,10 @@
 function create_startmenu_shortcuts($manifest, $dir, $global, $arch) {
     $shortcuts = @(arch_specific 'shortcuts' $manifest $arch)
     $shortcuts | Where-Object { $_ -ne $null } | ForEach-Object {
-        $target = [System.IO.Path]::Combine($dir, $_.item(0))
+        $target = $ExecutionContext.InvokeCommand.ExpandString($_.item(0))
+        if($target -eq $_.item(0)){
+            $target = [System.IO.Path]::Combine($dir, $_.item(0))
+        }
         $target = New-Object System.IO.FileInfo($target)
         $name = $_.item(1)
         $arguments = ''
@@ -11,7 +14,10 @@ function create_startmenu_shortcuts($manifest, $dir, $global, $arch) {
             $arguments = $_.item(2)
         }
         if ($_.length -ge 4) {
-            $icon = [System.IO.Path]::Combine($dir, $_.item(3))
+            $icon = $ExecutionContext.InvokeCommand.ExpandString($_.item(3))
+            if($icon -eq $_.item(3)){
+                $icon = [System.IO.Path]::Combine($dir, $_.item(3))
+            }
             $icon = New-Object System.IO.FileInfo($icon)
         }
         $arguments = (substitute $arguments @{ '$dir' = $dir; '$original_dir' = $original_dir; '$persist_dir' = $persist_dir })