Added DOI regex function to utils.py which is called in add_cmd.py
upon specifying a new DOI. DOI validation applies directly on
argument parsing by using a custom argparse.Action.
Allows aliases with descriptions.
Alias can be defined as currently supported and as subsections of the `[[alias]]` section of `conf.py` of the form:
```
[[[alias-name]]]
command = alias-command-definition
description = alias-description
```
Note that aliases defined this way must be placed at the end of the [[alias]] section or they will gobble up aliases defined in the current format. This is a limitation of `ConfigObj` sectioning.
Additionally, reverted FakeSystemExit subclassing Exception, but added
an explicit __init__ so that we can emulate the SystemExit.code
functionality without having to change the superclass.
Unittest just checks that both `pubs` and `pubs --help` raise a
`SystemExit` exception with error code 0. Due to how argparse
handles the `--help` keyword, this is the best way I could think to
provide test coverage without heavily modifying the parser structure
or the unittest infrastructure.
To ensure the `pubs` matches the behavior of `pubs --help`, it now
raises the same `SystemExit(0)` exception via `sys.exit(0)`. And
in order to catch it in the unittest, I had to modify the
`FakeSystemExit` behavior slightly.
Made subparsers not required in the main parser, but if no commands are parsed,
then the parser prints its help. When a command is present, the normal
functionality preserved.
Removed the single unittest that checks for this exact behavior.
Basically the validation takes care of setting results that
post-processing was relying on. Hence the validation should occur before
the postprocessing. It actually makes more sense to validate within
post-process.
The default behavior from the requests library is to use the guess from
chardet which is not always reliable while doi.org seems to always
return utf8 encoded data. It's unlikely that this changes without also
updating the header.
