Using a 4 line HD44780 LCD at Atmel controllers

Recently i found a nice C library for AVR controllers that enables to use LCD displays with HD44780
controller connected to the MC. Since i own a 4 line display with 2x HD44780 i wanted to get this
display working too. But two controllers were not supported. At the LCD2USB project sources which use a earlier stage of the libraries from Peter Fleury i found that support for two controllers (which is actually only to handly two enable lines) was hacked in. Since there are some more nice functions i merged the changes necessary to support two halfs of the display to a newer version of the library from Peter.
The result you can find attached. However it comes without warranty ;)