rsconstruct 0.9.0

Rust based fast build system
python files dependency analysis:
  for "import local_python_module" statements
  for dependency on other files with open(filename) or other functions.
  for import of external dependencies and generate external depenencies.

- when doing batch processing we are not using multi core. What can we do about it?

- do a pass of making the code more strict (whenever we relax strictness try to figure out if we can return the strictness)

- error handling.
    This is a big one.
    I want every processor to know how to parse the output of the tools it is running (if they are exernal) and collect errors in a organized fashion: file, line number, desription of the error, stack etc.
    then we can do something like: rsconstruct errors edit
    and it will launch an editors of my choice on all the previous errors.
    Internal processros will surely be able to collect all the errors into that predefined structure with no problems.
    rsconstruct errors show  will show the latest errors

- doing checksum of files.
    could we store the checksum next to the file on disk as extra data?
    are we using mmap when doing the checksum? Maybe we could speed up the checksum calculation this way.