Things to be done (feel free to contribute):

- image.c:
    - ReadImage(): Check the BAM
    - 1581: changing of subdirectories
    - selecting the disk name and ID
    - setupSideSectors() and checkSideSectors(): 1581 support
    - validate (Image *image, bool correct) must be written
      Sample output:
	Unallocated but used blocks:
	18,0 18,1 18,3

	Allocated but unused blocks:
	18,4

	Improper free blocks count on tracks:
	17 (10, should be 9)
	18 (1, should be 3)

- main.c:
    - interactive readline-based interface
    - writing a disk image to a non-existant directory doesn't report an error
