Tutorial: Train users to zoom in/out

[manaswisaha]

From Jon's recent comment on #531:

With the new GSV placement location in the tutorial, it's very hard to actually see this corner & the fact that there is no curb ramp. Perhaps we could have user zoom here (& train them in on zooming).

[manaswisaha]

Here is the sequence of screens for the new zoom feature implementation:

1: After labeling the first corner

2: After the user clicks on the zoom-in button

3: After labeling the curb ramp

4: After labeling the missing curb ramp

5: After clicking the zoom-out button

6: The next step

Looks good?
@jonfroehlich @misaugstad @maddalihanumateja

[maddalihanumateja]

Looks good to me.

[misaugstad]

Looks good!

[jonfroehlich]

I agree. We may feel differently once we use the interactive version. :)

[manaswisaha]

Great! I have merged it to develop. Closing via PR #642.