Improved serial handling, UI reflection of image mounting.

Faster serial handling. The arduino receives a range of bytes instead of a single byte at a time. Should now be as fast as a real 1541, or at least close to. More optimizations on serial handling can be done further on.

Added an about dialog. It will automatically show up every time a new version is released. There is also an application icon looking like a 1541 and a version resource added for windows targets. A C64 truetype font is embedded to the application for some UI controls like the image directory list.

Some source and README/NOTES commenting to shape up the things that is left to do.

Added skeleton class for .x00 (e.g. .P00) formats. This is just a placeholder for the code to be added further on.

Notification interface added so that UI can react to and reflect progress and mounting changes.

Displays current mounted image content, even automatically when CBM does the operations.
Some rearrangement of UI controls for better screen alignment and adaptation to windows resizing.

Realized that lots and lots of things are still to fix and to complete even before considering turbo support! Main focus right now is to get the most basic features of 1541 working, like the error channel and the saving support and at the same time finalize the UI on the host side. Some crashes and strange behaviors has been observed from time to time as well.

The D64 and T64 support is also very weak, no proper size checking and BAM handling implemented.