Log Message:
Update mate-terminal to 1.18.1:

### mate-terminal 1.18.0

  * NEWS: use consistent, project wide, markdown-like formatting
    to make generating release announcements easier
  * Add ability to close tabs with middle mouse button
  * Translations update

### mate-terminal 1.16.2

  * Bring back exit confirmation when there's a process running
  * Fix possible crash on window closing
  * Fix various issues with drag-n-drop of tabs
  * Encodings and keybindings dialogs: fix expand of content on
    window resize
  * Find, profile manager, profile prefs dialogs: fix runtime
    warnings about transient parent
  * Attach popup menus to their parent widgets (useful on Wayland)
  * Force X11 backend

### mate-terminal 1.16.1

  * Fix crash after detaching tab and then changing its title
  * Fix window positioning when using --geometry option
  * Translations update

### mate-terminal 1.16.0

  * Move to GTK+3, require GTK+ 3.14 and VTE 0.38 (API 2.91)
  * Drop GTK+2 code and --with-gtk build option
  * Use GtkAboutDialog instead of MateAboutDialog
  * Copy dconf and gsettings helpers from libmate-desktop and drop
    dependency on libmate-desktop
  * React on WM change only on X11
  * Fix lots of GTK+ deprecations
  * Some more fixes and cleanups
  * Translations update

### mate-terminal 1.14.1

  * man: add missing description of -x / --execute command line option
  * Translations update