Setting: Use only directory of origin

The origin member of the setting holds the originating _file_. Thus we
should strip of the file and take only the directory instead.
CliParser: Use correct origin

Since the CliParser specifies the origin as a directory and the Setting
uses a path to a file we need to append a directory seperator.

If there already is a directory seperator, it won't do any harm because
double directory seperators are usually parsed as one.
Setting: Return absolute path for path conversion
coalib: Use dirname instead of split

This is more efficient and straightforward.
SectionManager: Copy list before extending

If the list doesn't get copied, the local_bears list will actually be
extended. There will be a test added to avoid this in a later commit
after the SectionExecutor was added.
Collector: _check_item_availability -> _assert_...

This method is more of an assert than a check.
Bear: Do not inherit from Process

The Process class is not really useful and a Bear descendant will not be
executed as an own process.
ProcessSpawner: Do not inherit from Process

The Process class is not really useful and a ProcessSpawner will not be
used as a Process anyway.
ProcessSpawner: Remove Process dependency

Only a run method is needed. Enforcing some inheritance for this is not
really useful but rather blocking.
BearRunner: Don't inherit from Process

This inheritance is rather useless. See child commits of this one for
more info.
processes: Remove Process class

This class is not needed anymore. We can use multiprocessing.Process or
just ask for hasattr(obj, "run") to achieve the same.
processes: Remove ProcessSpawner

The ProcessSpawner makes some things a bit difficult to handle. After
trying to generalize and simplify it to use multiprocessing.Process'es I
concluded that the manual use of the Process derivatives is almost as
easy as using a ProcessSpawner. Thus I hereby remove it to improve
maintainability.
BearRunner: Inherit from multiprocessing.Process

This allows the BearRunner to be directly executed.
BearRunner: Receive global bears in a list

We cannot use the queue for that for various reasons:

* Queues cannot be sent through queues (global bears contain queues)
* It is slow to serialize such big objects through queues
processes: Add SectionExecutor (WIP)
processes: Add SectionExecutorTest