Add a new option --logpath

[bxsx]

Summary

This new option allows declaring a target directory for log files.
The default value is pulled from the --directory option.

IMPORTANT

This is a breaking change.

Old default behavior

gcexpert.log is stored in the current application directory

New default behavior

gcepxport.log is stored in the target directory of --directory, so the default is ./YYYY-MM-DD_garmin_connect_export

Motivation

By default, the application stores the exported activities in daily directories such as YYYY-MM-DD_garmin_connect_export.
By storing daily log files in the same directory as the activities, the user would have the full package of all files created by the app.

It is also worth noting that many operating systems have dedicated log folders, e.g. /var/log/ etc. This option allows for storing logs in such locations.

Background

Initial commit 7ab7125 by @cristian5th was cherry-picked from PR #66 where you can also find more discussion about this option.

[bxsx]

I added general cleanups for the parser in 57e830f. It can be reverted if not desired.

[pe-st]

Thanks, I will merge it soon