MATE and Cinnamon Rebuilt Plan

Since there has been some big changes in -current in the last few batches, i think it's time to test the latest snapshot against MATE and Cinnamon which intended for next Slackware releases. The addition of Python3, meson, and ninja really helped since some of the deps of both projects now requires them as mandatory requirements.

My request of libxslt also got approved and it was needed to build lxml 4.0 properly so at this moment, i'm building latest Cinnamon 3.4 packages against latest Slackware Current. Clem and other developers are still preparing for future Cinnamon 3.6 which is planned to be released by the end of this year (November/December). I hope to release the updated packages in the next few hours if everything goes smooth. Since python 3 got included, i updated some of the python packages to build python 2/3 bindings in the same package instead of splitting them into two packages.

As for MATE, i will merge 1.19-dev branch into master and this will build the latest snapshot of mixed MATE 1.18 and 1.19. Some dependencies have been bumped to the latest version as well since the libraries included in Slackware Current is sufficient to build the latest version. Some of them also migrates to meson, so it's a perfect timing to test them. MATE 1.20 is planned to be released in early 2018, so it will be targeting for next Slackware release. The minimum GTK+3 is probably raised to 3.20/3.22, so Slackware 14.2 will no longer qualified.

Just FYI, the next update of Slackware Live ISO of MATE variants will be based on a mix of MATE 1.18/1.19 built from master branch. Stay tune!!!