Add option to disable ctrl+<mouse-wheel> zooming

The built-in behavior of Ctrl+<Mouse Wheel> to zoom in/out the terminal
can not be disabled. This patch adds an option to disable this
behavior. (Default to the original behavior).

Original patch by Yichao Yu yyc1992@gmail.com
I made some changes - bugs are mine as usual
REVIEW: 107281
FIXED-IN: 4.11
GUI: