While we might never be able to have 100% of our code strict, we can at
the very least do it for all of our tests. This ensures that our tests
are using our API with the types as intended by the test author, and not
silently be cast to what our API requires.
Fix#3011. Some properties for Trendlines were omitted in the original request for this feature. Also, the trendlines sample spreadsheet included two charts. The rendering script 35_Chart_render handles this, but overlays the first output file with the second. It is changed to produce files with different names.
Adrien Crivelli
oleibman