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/libsize.py

@@ -0,0 +1,36 @@
+import os
+import sys
+
+# Internal build script for generating debugging test .so size.
+# Usage:
+#     python libsize.py file.so save.txt -- displays the size of file.so and, if save.txt exists, compares it to the
+#                                           size in it, then overwrites save.txt with the new size for future runs.
+
+if len(sys.argv) != 3:
+    sys.exit("Invalid arguments: usage: python libsize.py file.so save.txt")
+
+lib = sys.argv[1]
+save = sys.argv[2]
+
+if not os.path.exists(lib):
+    sys.exit(f"Error: requested file ({lib}) does not exist")
+
+libsize = os.path.getsize(lib)
+
+print("------", os.path.basename(lib), "file size:", libsize, end="")
+
+if os.path.exists(save):
+    with open(save) as sf:
+        oldsize = int(sf.readline())
+
+    if oldsize > 0:
+        change = libsize - oldsize
+        if change == 0:
+            print(" (no change)")
+        else:
+            print(f" (change of {change:+} bytes = {change / oldsize:+.2%})")
+else:
+    print()
+
+with open(save, "w") as sf:
+    sf.write(str(libsize))