Build procedure update plus introduction of Meson based builds.
* ps/build: (24 commits)
Introduce support for the Meson build system
Documentation: add comparison of build systems
t: allow overriding build dir
t: better support for out-of-tree builds
Documentation: extract script to generate a list of mergetools
Documentation: teach "cmd-list.perl" about out-of-tree builds
Documentation: allow sourcing generated includes from separate dir
Makefile: simplify building of templates
Makefile: write absolute program path into bin-wrappers
Makefile: allow "bin-wrappers/" directory to exist
Makefile: refactor generators to be PWD-independent
Makefile: extract script to generate gitweb.js
Makefile: extract script to generate gitweb.cgi
Makefile: extract script to massage Python scripts
Makefile: extract script to massage Shell scripts
Makefile: use "generate-perl.sh" to massage Perl library
Makefile: extract script to massage Perl scripts
Makefile: consistently use PERL_PATH
Makefile: generate doc versions via GIT-VERSION-GEN
Makefile: generate "git.rc" via GIT-VERSION-GEN
...