Fix a regression that was accidentally introduced
with v5.1.2 which could cause an issue URL to not
be successfully added to the source file when
dealing with a CRLF (Windows-style line endings)
file on Linux.

Partially addresses GitHub issue #245

Regardless of the OS on which the app is running,
respect the original line endings of the file
when writing back the issue URL. In the case of
a mixed line-ending file (e.g. both Windows-style
CRLF and Unix-style LF), the issue URL comment
line will use the line ending style of the TODO
comment line above it.

Partially addresses GitHub issue #245

Ensure alignment of issue URL line is correct even
when the TODO line had any number of tab
characters prior to the issue title

Addresses remaining sub-issues of and
closes GitHub issue #245

fix: handle different line endings