linecache2 does not conform to PEP 396 (missing __version__ string)

[ddriddle]

For our package management we use automated tooling to extract version numbers from python packages. I would like to request that you add the __version__ attribute version string.

PEP 396 states:

• On a case-by-case basis, standard library modules which are also released in standalone form for other Python versions MAY include a module version number when included in the standard library, and SHOULD include a version number when packaged separately.
• When a module (or package) includes a version number, the version SHOULD be available in the __version__ attribute.
• The __version__ attribute's value SHOULD be a string.

[ddriddle]

Submitted pull request #7 to address this issue.