Build Manager

The build manager (mypy/build.py) is responsible for orchestrating a mypy run.

The main entry point is the function build. It is given a set of files to process and the options/flags.

The build manager does these primary things:

1. Resolve imports to find all files that need to be processed (including stub files). Build an import dependency graph.
2. Figure out the order in which to process the files. We process import dependencies first before processing a module, so that we can resolve references to names defined in the imported modules.
3. Detect cyclic import dependencies, i.e. import cycles or strongly connected components (SCCs). Each SCC is processed as a unit, since each file in an import cycle could contains a reference to any other file within the cycle. (Note that each module is part of some SCC -- the simplest case is a SCC with a single file.)
4. Perform the different passes. This includes the Python Parser, Semantic Analyzer and Type Checker passes.
5. If running in incremental mode, deserialize each SCC instead of processing them if neither the SCC nor any transitive dependency has changed since the previous run (and config options haven't changed).
6. Return the ASTs of processed files, inferred types and any reported errors or notes to the caller.