--help now prints short help again, while help as a subcommand prints
long help.
--auth only does basic authentication, --auth-type is removed, and
--bearer does bearer authentication.
In theory, all panics after this should be bugs instead of normal
error conditions.
The error reporting may still need finetuning. For example, if the
hostname doesn't resolve you get a redundant traceback:
```
Error: error sending request for url (http://bad-hostname/): error trying to connect: dns error: failed to lookup address information: Name or service not known
Caused by:
0: error trying to connect: dns error: failed to lookup address information: Name or service not known
1: dns error: failed to lookup address information: Name or service not known
2: failed to lookup address information: Name or service not known
```
This commit also fixes all of the remaining Clippy warnings.
Resolves#14 (?)
