Version 7 'Providence'

This release involves a lot of internal code work and restructuring to generally improve the project. But there are some new features too!

• You can now trash across filesystems, solving issue #1. The solution I opted for isn't the most elegant, but it is simple and effective.
• There is now a -d flag for trashing empty directories. This increases compatibility with rm further.
• Better error messages that more accurately mirror rm's, on the off chance you're parsing its output.
• --version and --help now provide license and repo information.
• --help is now formatted better.

More importantly, this is also the first named release of trash-d! I'm going with a naming scheme based on video game bosses, and this one is named after Providence from Risk of Rain.

This release was also so big that we skipped 2 version numbers in the process!