Add possibility to read command line arguments from file

[brycelelbach]

[reported by hkaiser] [Trac time Wed Aug 17 12:53:05 2011] Adding the possibility to specify a file on the command line to any HPX application greatly simplifies launching those on clusters. Two things need to be implemented:

• any @file command line argument will have to read the content of file and insert each line as an argument onto the command line
• have any HPX application look for app.cfg starting from the current working directory upwards (where app is the basename of the application (either argv[0] or as specified to hpx::init). This file will be treated as if it was specified as the first argument: @app.cfg.

[brycelelbach]

[comment by hkaiser] [Trac time Wed Aug 17 16:58:33 2011] Resolved in rev. [5325]