The output is now limited to 80 characters; this is useful when cat'ing to a
file and terminal.get_size() is called. The previous behaviour was to always
output according to the terminal width, something that probably isn't what
someone usually wants when outputting to a file.
This was added because "git blame -C -C" really takes a lot of time and
something is needed to indicate that gitinspector is actually running during
this stage.
The progress text is not shown if stdout points to a non-terminal.
