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.
It should now be able to handle multi-line comments that are only on one line.
Furthermore, it should also handle multi-line comments from languages such as
python (where the identifiers for comment begining/end are identical).
If any missing files are detected during analysis, gitinspector reports them
in a list. If, on the other hand, the --checkout-missing option is supplied,
gitinspector will try to checkout any missing files instead.
