miniterm: tweak read loop (fewer I/O calls)
diff --git a/serial/tools/miniterm.py b/serial/tools/miniterm.py
index b7f23cd..d21c8ca 100644
--- a/serial/tools/miniterm.py
+++ b/serial/tools/miniterm.py
@@ -332,7 +332,8 @@
         """loop and copy serial->console"""
         try:
             while self.alive and self._reader_alive:
-                data = self.serial.read(1) + self.serial.read(self.serial.inWaiting())
+                # read all that is there or wait for one byte
+                data = self.serial.read(self.serial.inWaiting() or 1)
                 if data:
                     if self.raw:
                         self.console.write_bytes(data)