add Archlinux clang+cmake, gcc+meson docker builds to scripts
Ubuntu 14.04 docker build: upgrade cmake and Qt tools
rename Docker image Debian/Sid to Buster. Sid is always testing release, see https://www.debian.org/releases/
remove Debian Jessie docker image - minimum supported CMake version is 3.1 that is not available in Jessie
use github repository as default in debian sid
remove workaround for meson < 0.45
move Qt client classes to osmscout namespace
free text indexes (Marisa) are optional, Qt database manager should not require it