Create stub for core script, Python package folder

Decided on name "csdb" for *checksum database*.
Add stubs for Main, ConfigMgr

The root `csdb.py` will serve as an entry point for csdb. Create the
module `Main`, which contains the `main()` function and provides all UI
functionality, and `ConfigMgr`, which will handle config files and
command line arguments.
Add stubs for basic commands
Merge branch 'feature/create-core-scripts' into develop
Add basic options processing

Action verbs are now recognized (first one to appear is accepted, rest
is treated as paths). Options (startin with a dash -) are caught (and
currently ignored); pure double-dash (--) recognized to mark "only
paths after this" as per *nix convention.
Add options dict, expand-paths function

Add a basic options dictionary (no key filtering/pre-processing at the
moment) with a getter function and a `__getitem__` to use the indexer
on the ConfigMgr object.

Add the `expandInputPaths` function to turn directory paths into lists
of contained files (recursively or not). This is the basic function
from the existing script, which is hard-coded to `/` as path delimiter.
This should be fixed.
Add remaining existing functionality

Add the checking functionality that has already existed in the original
script. This includes the ability to check the SHA1 and CRC against an
existing (populated) SQLite database.

Calling csdb with no arguments will default to the 'help' action
(currently not implemented, but it will tell you that).

Calling csdb with arguments when the first argument is not a command
verb will default to the 'check' action for convenience and backwards
compatibility.
Remove old one-shot version of the script
Merge branch 'feature/integrate-existing-functionality' into develop