PickleShare - a small 'shelve' like datastore with concurrency support

Like shelve, a PickleShareDB object acts like a normal dictionary. Unlike shelve,
many processes can access the database simultaneously. Changing a value in
database is immediately visible to other processes accessing the same database.

Concurrency is possible because the values are stored in separate files. Hence
the "database" is a directory where *all* files are governed by PickleShare.

Both python2 and python3 are supported.

Example usage:

```python

from pickleshare import *
db = PickleShareDB('~/testpickleshare')
db.clear()
print("Should be empty:", db.items())
db['hello'] = 15
db['aku ankka'] = [1,2,313]
db['paths/are/ok/key'] = [1,(5,46)]
print(db.keys())
```

This module is certainly not ZODB, but can be used for low-load
(non-mission-critical) situations where tiny code size trumps the
advanced features of a "real" object database.

Installation guide:

```sh
pip install pickleshare
```

Or, if installing from source

```sh
pip install .
```