Answer a String containing the required segment of the file
copyFrom: from to: to
Answer a String containing the given subsegment of the file. As for
streams, from and to are 0-based.
file
Answer the File object for the file containing the segment
fileName
Answer the name of the file containing the segment
filePos
Answer the position in the file where the segment starts
relocateFrom: startPath map: map
If the path starts with startPath, remove that part of the path.
map is a Dictionary that is used so that equal filenames stay equal,
without increasing the amount of memory that the image uses.
size
Answer the length of the segment
withFileDo: aBlock
Evaluate aBlock passing it the FileStream in which the segment
identified by the receiver is stored