Redesigned visualization

[integraledelebesgue]

Closes #46

Changes

• New Visualizable protocol indicates that object can be drawn on a frame
• All Results implement Visualizable
• Visualizer is no longer implementing the drawing logic for particular Results. Instead, it calls methods from Visualizable on them and accumulates obtained drawings for each frame.
• calibrate command now expects a workspace argument and positive number of videos, identically to process
• calibrate and process save annotated videos:
  * calibrate draws chessboard corners on analyzed frames
  * process draws marker bounding boxes, ids and local coordinate axes
• Writer now takes Path instead of str as a destination