Change keyboard shortcut for close tab in Chromium

Ctrl-F4 is used because Ctrl-w is used for "delete one word"
Change key bindings so that "e" doesn't conflict with default command

Key binding to edit NeoSnippet snippet file is changed because "es<space>"
conflicted with the default "e" command. VimFiler command "vf" is also changed
to <Leader>vf for the same reason.