Description

Added heuristics for .bf extension.

Added the .bf extension to Befunge.

Added the following Befunge-93 samples:

• aturley.bf by Andrew Turley (CC0 license), fetched from https://github.com/catseye/Befunge-93/blob/master/eg/aturley.bf
• beer7.bf by Wim Rijnders (CC0 license), fetched from https://github.com/catseye/Befunge-93/blob/master/eg/beer7.bf
• befunge3.bf by Ben Olmstead (CC0 license), fetched from https://github.com/catseye/Befunge-93/blob/master/eg/befunge3.bf
• cascade.bf by Chris Pressey (CC0 license), fetched from https://github.com/catseye/Befunge-93/blob/master/eg/cascade.bf

And Befunge-98:

• mycorand.bf by Matti Niemenmaa (MIT license), fetched from https://github.com/Deewiant/Mycology/blob/master/mycorand.bf

For future reference: I have not included the (rarer) extensions .b93 and .b98, but there are samples for it under liberal licenses here:

• mycoterm.b98 by Matti Niemenmaa (BSD license), fetched from https://github.com/Deewiant/Mycology/blob/master/mycoterm.b98
• Euler_Problem-001.b93 by Mike Schwörer (MIT License), fetched from https://github.com/Mikescher/Project-Euler_Befunge/blob/master/processed/Euler_Problem-001.b93

Checklist:

• I am associating a language with a new file extension.
  • The new extension is used in hundreds of repositories on GitHub.com
    • Search results for each extension:
      • https://github.com/search?utf8=%E2%9C%93&type=Code&ref=searchresults&q=extension%3AFOOBAR+KEYWORDS+NOT+nothack
  • I have included a real-world usage sample for all extensions added in this PR (see above)
  • I have included a change to the heuristics to distinguish my language from others using the same extension.