Switched to full tracks instead of sectors, and at high baud rate.

Uses cngsoft's CALLBCA1 loader and 4000 baud, only 13s per track!
Pass final track lengths in DIB and make loader use them.

Prereq for doing track compression, and proper double-to-single side
handling. We now also check loaded track is the right one and prompt
for a rewind if we've overshot.
Set DEAFBCA1 for some more baudrate headroom.
Modified 2cdt no longer required.
Compress tracks with exomizer for major speed gains.
Reorganise build, create proper Makefile
Build loader files into executable
Abstract out exomizer and 2cdt paths in Makefile