tmux upgrade fix for iTerm2 from 2.9 to 3.1b

Fix tmux configuration issues when upgrading iTerm2 and tmux version 2.9 to 3.1b

unbind } ==> unbind "{"
unbind { ==> unbind "{"
bind \ if '[ ===> bind \\ if '[

Scrolling in iTerm and tmux, fixed by

Solved by enabling ‘enable mouse reporting’ in Preferences > Profile > Terminal > Enable Mouse Reporting