Prevent raw errors and use logging instead

[orhun]

Describe the bug
In some cases menyoki might encounter an error and terminate itself without handling the error. (#20) For that, it often uses expect and it causes to print raw Rust errors. These cases should be handled more elegantly and errors should be printed to stdout with log::error macro.

To Reproduce
Steps to reproduce the behavior:

1. Run menyoki rec -f -c 0
2. Press ESC
3. See error:

thread 'main' panicked at 'No frames found to save', src/app.rs:453:28
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
Aborted (core dumped)

Expected behavior

[2021-03-09T11:20:04 ERROR menyoki::app] No frames found to save.

System Information

• OS: Arch Linux x86_64 5.11.2-arch1-1
• Rust Version: 1.50.0-stable
• Project Version: 1.2.1

[orhun]

v1.4.1:

[2021-07-02T14:08:57 INFO menyoki::record] Recording 20 FPS...
^[[2021-07-02T14:08:58 WARN menyoki::record] User interrupt detected.
[2021-07-02T14:08:58 ERROR menyoki] Frame error: `No frames found to save`