Improve handling ambiguous device names

* Adds the `phys` info for the device to the list
* Orders names by name first then by the eventXXX number component so
  that there is a "stable" ordering for a given set of inputs
* When a name has ambiguous matches, warnings are logged to advise the
  user how to resolve them.

Example:

```
; cat /tmp/evremap.toml
device_name = "Power Button"
```

```
sudo ./target/debug/evremap remap /tmp/evremap.toml
 2021-11-24T10:04:40.885 ERROR evremap > Short delay: release any keys now!
 2021-11-24T10:04:43.084 WARN  evremap::deviceinfo > The following devices match name `Power Button`:
 2021-11-24T10:04:43.084 WARN  evremap::deviceinfo > DeviceInfo { name: "Power Button", path: "/dev/input/event0", phys: "PNP0C0C/button/input0" }
 2021-11-24T10:04:43.084 WARN  evremap::deviceinfo > DeviceInfo { name: "Power Button", path: "/dev/input/event1", phys: "LNXPWRBN/button/input0" }
 2021-11-24T10:04:43.084 WARN  evremap::deviceinfo > evremap will use the first entry. If you want to use one of the others, add the corresponding phys value to your configuration, for example, `phys = "LNXPWRBN/button/input0"` for the second entry in the list.
 2021-11-24T10:04:43.085 ERROR evremap::remapper   > Going into read loop
```

refs: #2
closes: #3

1 files changed, 4 insertions, 0 deletions

diff --git a/README.md b/README.md
index 6656baf..0b4b2ca 100644
--- a/README.md
+++ b/README.md
@@ -29,6 +29,10 @@ Here's an example configuration that makes capslock useful:
 # on your system.
 device_name = "AT Translated Set 2 keyboard"
 
+# If you have multiple devices with the same name, you can optionally
+# specify the `phys` value that is printed by the `list-devices` subcommand
+# phys = "usb-0000:07:00.3-2.1.1/input0"
+
 # Configure CAPSLOCK as a Dual Role key.
 # Holding it produces LEFTCTRL, but tapping it
 # will produce ESC.