Improve preferences interface

[jonstod]

Describe the current limitation
In its current state, the preferences interface takes hours worked and break time hour amounts in the 00:00 format and does not accept other formats (8:00, 8, 8.5, etc.).

Describe the proposed feature or enhancement
Enable the user interface to process time durations in the formats mentioned above. For example, so that the user may enter "8", "8:30", or "8.5" for hours worked rather than strictly "08:00" or "08:30".

Additional context
It appears that the processing/storing of user preferences is done on the Electron side of things, which I am not exactly comfortable working with. One possible solution would be to use an HTML combo box in /src/preferences.html so that it preserves the ability for users to enter custom values, while providing suggested values that they can select and autofill the fields with (and also showing them the format required).

[TaranDev]

Hi @tupaschoal, I'm hoping I can work on this issue, specifically allowing input in different formats for the time fields. Would it be possible to assign it to me?

[tupaschoal]

Sure