mate-themes 3.22.22 release

Changes since the last release: v3.22.21...v3.22.22

• Travis CI: use Ubuntu 20.04 instead 19.10
• Travis CI: Fix build error with arch
• Travis CI: enable irc notifications with broken builds
• [ci] fix release tarball on travis CI failed
• TraditionalOk/Green: Fix title_border bottom attribute
• Traditional and Menta theme families: Resolved Caja sidebar display regressions

Several lines in these themes, seemingly related to historical overlay
scrolling issues, have been removed. These lines were causing the doubling
in height of some rows in the Caja Places, Tree, History and Bookmarks
sidebars in all themes, and the chopping off of the left side of said
Caja sidebars in the Traditional family of themes.

• Travis CI: enable irc notifications with tagged commits
• gtk-widgets.css: Add the missing .context-menu class
• Blue-submarine: Use procedural adaptive-sized icons
• Green-Submarine: Use procedural adaptive-sized icons
• Remove USE_MATE2_MACROS from autogen.sh (legacy)
• travis CI: use rolling tag for ubuntu docker image
• Remove the execution bit
• Set gtk-print-preview-command in settings.ini
• i18n: icon theme ContrastHigh
• build: allow users to disable gettext support (--disable-nls)
• Traditional themes: fix tooltip shadow on openindiana
  The compositor doesn't apply the shadow mask if border-radius is 0

closes #255

• tx: sync with transifex
• release 3.22.22