lightirc: many many things

* Add disconnect option to disconnect from server - this is within the
server channel activity - still needs implementing when the server is
long pressed on the list - closes #1
* Make many many things private in the spirit of object orientation -
add getters and setters to compensate
* Make service unkillable (almost) by making it run in the foreground -
this also needs a notification to be displayed so kills 2 birds with 1
stone - closes #7
* Share data between server and listeners better - closes #13
* Refactor many variables to make the code much neater