tweak portable install; support renaming installation dir (#359)

install-portable.bat

@@ -1,5 +1,8 @@
 @echo off
 
+echo Installing WSL Terminal Portable
+echo Select target folder in popup dialog ...
+
 set sel="Select folder to place installation of portable wsltty"
 
 for /f "usebackq delims=" %%f in (`powershell "(new-object -COM Shell.Application).BrowseForFolder(0, '%sel%', 0, 0).self.path"`) do set f=%%f
@@ -14,15 +17,18 @@ if "%f%"=="" (
 	exit
 )
 
+rem call main installation
 call install "%instdir%" "%instdir%" /P
 
 rem create shortcut
-cd /D "%instdir%"
 set instpath=%instdir:~2%
+cd /D "%instpath%"
 set target=%%COMSPEC%%
 set minttyargs=/C bin\mintty.exe --WSL= --icon=/wsl.ico --configdir=. -~
 set bridgeargs= -
-set wdir=%instpath%
+rem set wdir=%instpath%
+rem let mkshortcut set working directory to empty:
+set wdir=.
 set icon=%instpath%\wsl.ico
 cscript /nologo mkshortcut.vbs "/name:WSL Terminal Portable"
 

mkshortcut.vbs

@@ -29,10 +29,14 @@ rem wscript.echo "minttyargs: " & minttyargs
 rem wscript.echo lnk.Arguments
 
 rem Start in:
+rem Working directory; Arguments.Named would take "/wdir:C:\..." parameters
 rem wdir = Wscript.Arguments.Named("wdir")
+rem Working directory; function ExpandEnvironmentStrings cannot pass empty
 wdir = wshell.ExpandEnvironmentStrings("%wdir%")
 if IsEmpty(wdir) then
   lnk.WorkingDirectory = "%USERPROFILE%"
+elseif wdir = "." then
+  lnk.WorkingDirectory = ""
 else
   lnk.WorkingDirectory = wdir
 end if