Jonno Downes updates dsktool.rb to 0.4.2

Jonno Downes has released dsktool.rb 0.4.2, a command line tool and library (written in Ruby) for manipulating DSK images.

The major changes in this version are:

* DOS 3.3 support now read/write
* NADOL support (read/write)
* ProDOS support (read only)
* Pascal support (read only)
* Hi Res Graphics converted to PNG

Jonno has requested all feedback and bug reports to be posted to comp.sys.apple2 or the RubyForge tracker site.