MediaConverter: Update copyright year
MediaConverter: Make the window not vertically resizable
MediaConverter: Set ListView min size font relative
MediaConverter: Set initial text in constructor
MediaConverter: Set slider percentage live
MediaConverter: Add label and control explicitly
MediaConverter: output box fixes size, truncate long path

Update path truncation if output box is resized.

Other changes:
* Set duration text box to a smaller explicit width
* Increase min sources width and replace magic constant
* Some style fixes, especially to comments
MediaConverter: Set slider widths explicitly
MediaConverter: Style fixes