Improve startup behaviour and commandline options so that subl can replace system text editor.

It would be useful to have a way to ask Subl to just display the file passed in the commandline and ignore for the moment the setting for reopening files etc. A switch to ask it to act just as gedit would do.
Currently with a slightly old version of GTK in Linux Sublime Text wont detect it is already running when launched. This has many side effects as duplicating all the windows if launched twice. Such a switch could help in that situation too.