add explorer restart support

fixed the bug that when explorer.exe crashed, the tray icon disappear.
fixed range request support

fixed the bug that lead to failed range request in some cases
start and stop command in context menu

Add two entries in context menu of tray icon
restrict singleton in windows

Only one mongoose allowed, and make service control more specific in a
mongoose way. When a application run, it will check whether a service
has been created. If a service exists, it change to a monitor for the
service, otherwise it will do the server job.