Newly created session doesn't use .tmux.conf settings and bindings #15
Description
I've installed Tmux 2.3 via Linuxbrew.
When I use tmux-sessionist and create a new session using prefix C the session gets created but the prefix defaults back to Ctrl+b instead of my chosen prefix. If I use <default prefix> R then it reloads the ~/.tmux.conf and everything works as expected again.
While debugging I actually discovered that even doing this without some of the extra convenience methods of tmux-sessionist has the same issue, i.e. using prefix :new-session -s "sessionname" has the same issue.
The fix seems to be adding \; source-file ~/.tmux.conf to the end of the new-session command to ensure that the config file with the customized prefix gets properly loaded. I'll submit a PR with this change as it should be zero impact and will fix this behavior nicely.