Automatically set RUST_LOG only under debug builds

Syngestures 1.0.1

This minor update to `syngestures` includes many under-the-hood
improvements that speed up processing and reduce CPU usage throughout
the duration of a click/gesture.

* Improved `evtest` output handling. `syngestures` was already very
  resource efficient, but this update further reduces calculation and
  CPU usage for the duration of touchpad events.
* Updates to underlying libraries (cargo dependencies) to keep
  everything mantained and running smoothly.
* Fixed some typos in the README and in some of the error messages
  emitted by `syngestures`.
* More helpful command line output when `syngestures` is run without
  arguments to help first-time users.
* Implemented `--help` and `--version` command line switches (and their
  short versions `-h` and `-V`, respectively).

Syngesture 1.0

This is the first "official" release and will have accompanying Linux
binaries precompileda and uploaded to the GitHub repository.

See README and sample configuration file for more information.