Merge various improvements from genbtc's version

* group orders below 0.6 (we really should make this configurable at
  some point)
* remove USD volumes (I kind of liked them, but I'll admit they're not 
  crucial for trading)
* gain screen estate by tabbing authentication stuff
* customizable application log (filters)
* add bitcoin icon
* make the price column 5 decimals 
* make buy/sell price edit box 5 decimals
* correct windows start script
* fix the code that inserts order-Id's into the edit box to better
  identify the last order
Correct number of decimals in some places.