python-snakefood: add 1.4

* Generate dependencies from Python code, filter, cluster and generate
  graphs from the dependency list

* Tools included:
  - sfood:
      Given a set of input files or root directories, generate a list of
      dependencies between the files;
  - sfood-graph:
      Read a list of dependencies and produce a Graphviz dot file. (This
      file can be run through the Graphviz dot tool to produce a
      viewable/printable PDF file);
  - sfood-cluster:
      Read a list of dependencies, a list of file clusters, and output a
      list of simplified (clustered) dependencies.
  - sfood-checker:
      Analyze the source code with the AST and list unused or redundant
      imports.
  - sfood-imports:
      Find and list import statements in Python files, regardless of
      whether they can be imported or not.

Signed-off-by: Tim Orling <TicoTimo@gmail.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>