parseCommand: Spaces at the beginning of a command should no longer make the shell crash

src/fsh.nim

@@ -191,6 +191,7 @@ proc parseCommand(cmd: string): seq[string] =
         newitem.add(strm.readSubstitution.newStringStream.substitute)
       of '$': result.add(strm.readVariable.evalVariable)
       of ' ':
+        if (result == @[]) and (newitem == ""): continue
         result.add(newitem)
         newitem = ""
         discard strm.skipSpaces()