Edited help output from commands + assorted (minor) edits

* Help output is now closer to (equivalent with…?) modern conventions in other CLI programs
* `Summary…` and `Usage…` spacing adjusted for consistency (and slightly easier reading)
* Whenever a program prints a path, file, or URL, the path/file/URL is printed on a separate line (for easier reading and copy-pasting)
* Minor edits to phrasing
* Minor edits to source spacing and linebreaks (slight improvements for readability)