Stop using setuptools' "scripts" feature, now obsolete and bound to
create issues in the future, and use the newer
entry_point/console_script mechanism instead to create the same
command-line tool.
Preserve the "scripts/create-script.py" executable source for
development environment convenience.
(cherry picked from commit 059030ba0e)
This commit stops considering Langkit_Support as a generated project:
* move the "langkit/support" directory to "support" (not
"langkit_support" for convenience with tab-completion);
* move the meat of the "langkit_support_gpr.mako" template to the static
"langkit_support.gpr" file, and remove the template;
* remove the "build-langkit_support.py" script and all the corresponding
libmanage.py/langkit_support.py code;
* enhance the top-level "manage.py" script to build/setenv
Langkit_Support and import the packaging tools from
"build-langkit_support.py".
From now on, Langkit_Support is a really a standalone library project,
and thus a "real" dependency for Langkit-generated libraries.
TN: T914-012
Remove the --enable-shared, --enable-static, --disable-shared and
--enable-static command-line options and introduce the --library-types
one. Keep the previous default behavior (build only shared libs by
default).
TN: S402-020
