Issue #178 implementation

[corot]

When parsing the filename tag, do not throw and exception if not found on stdr_resources/resources, but also search on the directory containing main file.

Please note that this is my first contact with the stdr code, and it's possibly I misunderstood how files parsing works! If so, please tell me and simply drop this PR.

[czalidis]

LGTM, @etsardou ?

@corot Some minor comments:

• The extractDirectory function actually implements the unix's dirname functionality. Should it be renamed in order to be clear what's the functionality? (Also you could use parent_path from boost::filesystem)
• Can you squash your commits to one?

[corot]

:+1:

[czalidis]

Closed in favor of #180.