Hardcopy of pybind11 instead of using git submodules (#552)

* removed pybind as submodule
* added hardcopy of pybind11 2.10.0
* rename pybind11 folder to avoid conflicts when changing branch

Co-authored-by: Dhanya Thattil <dhanya.thattil@psi.ch>

libs/pybind/tools/setup_global.py.in

@@ -0,0 +1,59 @@
+#!/usr/bin/env python3
+
+# Setup script for pybind11-global (in the sdist or in tools/setup_global.py in the repository)
+# This package is targeted for easy use from CMake.
+
+import glob
+import os
+import re
+
+# Setuptools has to be before distutils
+from setuptools import setup
+
+from distutils.command.install_headers import install_headers
+
+class InstallHeadersNested(install_headers):
+    def run(self):
+        headers = self.distribution.headers or []
+        for header in headers:
+            # Remove pybind11/include/
+            short_header = header.split("/", 2)[-1]
+
+            dst = os.path.join(self.install_dir, os.path.dirname(short_header))
+            self.mkpath(dst)
+            (out, _) = self.copy_file(header, dst)
+            self.outfiles.append(out)
+
+
+main_headers = glob.glob("pybind11/include/pybind11/*.h")
+detail_headers = glob.glob("pybind11/include/pybind11/detail/*.h")
+stl_headers = glob.glob("pybind11/include/pybind11/stl/*.h")
+cmake_files = glob.glob("pybind11/share/cmake/pybind11/*.cmake")
+headers = main_headers + detail_headers + stl_headers
+
+cmdclass = {"install_headers": InstallHeadersNested}
+$extra_cmd
+
+# This will _not_ affect installing from wheels,
+# only building wheels or installing from SDist.
+# Primarily intended on Windows, where this is sometimes
+# customized (for example, conda-forge uses Library/)
+base = os.environ.get("PYBIND11_GLOBAL_PREFIX", "")
+
+# Must have a separator
+if base and not base.endswith("/"):
+    base += "/"
+
+setup(
+    name="pybind11_global",
+    version="$version",
+    packages=[],
+    headers=headers,
+    data_files=[
+        (base + "share/cmake/pybind11", cmake_files),
+        (base + "include/pybind11", main_headers),
+        (base + "include/pybind11/detail", detail_headers),
+        (base + "include/pybind11/stl", stl_headers),
+    ],
+    cmdclass=cmdclass,
+)