#829 Allow option to remove "x" from tabs

[Alex Tang]

Tabs have two settings: "compact" and non-compact. The compact mode only shows the tab name, while the non-compact mode shows the tab name, the number of the tab, and a "close" "X".

I like the numbers on the tabs because it tells me which keyboard shortcut to use "cmd-#", however I hate those close "x" icons because it's much too easy to click on them when you want to switch to a particular tab.

I'd like a config option to remove the "X" but not remove the tab number.

Thanks!