Few patches to fix deprecated functionality and error messages

[Wouter Van Rooy]

I don't know if this project is still active but I've prepared a few patches to fix the  vte_terminal_fork_command deprecation and fix some glib error messages and build warnings.

Wouter Van Rooy

[Calvin Morrison]

Wouter,

Thank you! The project is only not "alive" because it is working fine
on my box with no need for development :-P. I did notice recently that
there were some warnings. I will go ahead and apply these patches to
our repositories.

Calvin Morrison

[Calvin Morrison]

patches merged.

commits:
8ba24d8aa07a
2686bd5702f3
556b6af833f3