fix(new_connection): save adjusted screen to user's description

Previously, after adjusting screen it was not saved into description of
corresponding user.
fix(resize): save adjusted screen to user's description
fix(minimap): allow canvas html element auto adjust to canvas size
feat(minimap_style): add border to minimap
feat(minimap): draw all screens on minimap

Show current user's and other users' screens on minimap.
Minimap is aut adjusting to changes in workspace.
fix(drawMinimap): draw minimap on other workspace adjust
fix(drawMinimap): take on() method from drawMinimap()

When method on() was inside drawMinimap(), it was called few times, and
it was adding same handlers for the same event. So when event was
fired, there was few handlers to handle this event.
fix(vars): make MAX_CANVAS_WIDTH and scale be global
feat(drawClients): move code to new function

Move code to draw clients from on() to new function drawClient()
feat(minimap): add balls on minimap

Position of balls is shown on minimap. After first client touches ball,
everyone can see its position.