bitmap outline-only rectangles should have square corners

[fsih]

Expected Behavior

In 2.0 and in the vector editor, rectangles have pointy corners

Actual Behavior

The corners look rounded in 3.0

How to fix

The line to change is here
https://github.com/LLK/scratch-paint/pull/920/files/c72159ab2705d912be6406761987e81238ab0da2#diff-7061317e88929cb3cf483324379efdc2R139
The conversion to bitmap code would also need to change to not use the line tool

Steps to Reproduce

1. Open costume tab
2. Convert to bitmap editor
3. Click rectangle tool
4. Click outlined

Operating System and Browser

e.g. Mac OS 10.11.6 Safari 10.0