python_cc_reader module to python3 (#4590)
Submodule update for the tools repository which includes a large structural change to the `python_cc_reader` module and its conversion to python3.
The directory structure for the `python_cc_reader` module is now as follows:
```
tools/
python_cc_reader/
python_cc_reader/
beauty/
code_improvement/
cpp_parser/
external/
inclusion_removal/
library_splitting/
tests/
utility/
```
The rationale for this dirname-within-dirname structure was given on this page:
https://docs.python-guide.org/writing/structure/
At the top level `python_cc_reader`directory live the user-level scripts such as `library_levels.py` and `beautify_changed_files_in_branch.py.` Within the lower level `python_cc_reader/python_cc_reader` directories live the modules that actually do all the heavy lifting.
These scripts are imported by a number of other scripts in the `tools` repository, and I have updated all of these scripts.