HLedger haskell port now being mirrored on GitHub

[John Wiegley]

I finally got git-darcs-import to build, so there is now a Git mirror  
of Simon Michael's Haskell port of ledger on GitHub:

    http://github.com/jwiegley/hledger

Also, I've added a Ports page to the Wiki, to show the 5 different  
Ledger derivates I currently know about.

John