Use DrawingVisual in DescriptionCanvas
Set descriptions to DescriptionCanvas height
Progress commit: Partial waveform drawing
Use canvasWidth instead of interval width
Fix binding error due to refactor
Add PenFactory
Draw interval titles to canvas
Remove colour change logic from interval classes

It was old and no longer used.
Add BrushFactory
Use DrawingVisual in NumberLineCanvas
Make numberline timestamps more readable
Change image adding procedure

Canvases no longer remove and add new images, instead they contain a
readonly reference to a single image whose source gets modified instead.
Reset canvas images when there is nothing to draw
Redraw timeline after setting interval location

Removes an unessessary draw of the timeline because the timeline being
drawn properly depends on the video being opened, not the project being
loaded.
Add TimelineControl
Add missing ScrollViewer
Add some logic to TimelineControl

Add basic methods and things
Move more Timeline logic into TimelineControl

Move position and TimelineControl events
Move remaining Timeline logic to TimelineControl

Concerns have been separated.