Add FPS support to the GUI

[Morikko]

Motivation

FPS must match the actual movie to keep the correct timing. Having this information is useful when there is no hash match.

Implementation

1. Disable by default
2. Support GUI + Terminal mode
3. Support auto mode

Example

[emericg]

I'm really sorry I completely missed this pull request when it was sent... It's really clean and also really useful, thank you for submitting this!