Do not show disabled keyboard shortcuts #282

It would be nice if bpython did not display disabled keyboard shortcuts. For example, I disable Pastebin via the following.

[keyboard]
pastebin=

I end up with the following in my bpython screen. Note the strange <> Pastebin.

 <C-r> Rewind  <C-s> Save  <> Pastebin  <F9> Pager  <F2> Show Source

• Bitbucket: https://bitbucket.org/bobf/bpython/issue/282
• Originally Reported By: Steven Myint
• Originally Created At: 2014-05-08T15:48:03.749