Deprecate .timecardrc and .timecard in favor of user dirs

[CodeMouse92]

• Deprecate storing settings in .~/timecardrc in favor of the user config directory, e.g. ~/.config/timecard/settings.conf.
• If new default location doesn't contain settings.conf, fall back on .timecardrc and automatically migrate its contents.
• Add line comments to config files, so we can leave comments on old config files that they were migrated.

Also, change the default log location from ~/.timecard to the more standard location of (e.g.) ~/.local/share/timecard/.