Merge branch 'ps/build'

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
  ...

Documentation/CodingGuidelines

@@ -583,7 +583,7 @@ For C programs:
    Run `GIT_DEBUGGER=1 ./bin-wrappers/git foo` to simply use gdb as is, or
    run `GIT_DEBUGGER="<debugger> <debugger-args>" ./bin-wrappers/git foo` to
    use your own debugger and arguments. Example: `GIT_DEBUGGER="ddd --gdb"
-   ./bin-wrappers/git log` (See `wrap-for-bin.sh`.)
+   ./bin-wrappers/git log` (See `bin-wrappers/wrap-for-bin.sh`.)
 
  - The primary data structure that a subsystem 'S' deals with is called
    `struct S`. Functions that operate on `struct S` are named