"Auto Show Serial Monitor"

Added support for automatically showing the Serial Monitor window. This support is controled by a checkbox menu item in the Tools menu ("Auto Show Serial Monitor"). The feature is disabled by default and is tracked by a boolean "serial.auto_show_monitor_window" in Preferences.txt. When "auto show" is disabled the Serial Monitor window behavior is unchanged (i.e. if you don't enable "auto show" the IDE will work as it always has).

NOTE: I do not know how to handle the internationalization issues (adding the menu item text to the various string resource files).