simple fastplotlib example

[kushalkolar]

continued from #88, rebase got messy

This works and should be ready to go!

[coveralls]

Pull Request Test Coverage Report for Build 4507192899

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 30 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.05%) to 57.061%

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Files with Coverage Reduction	New Missed Lines	%
improv/cli.py	30	66.5%

Totals
Change from base Build 4504290642:	-0.05%
Covered Lines:	990
Relevant Lines:	1735

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💛 - Coveralls

[kushalkolar]

@clewis7 will make a test using the nbmake plugin

[kushalkolar]

@clewis7 generate a 2D sine wave with a wavelength that depends on if the number is even or odd

[kushalkolar]

instead of doing two different wavelengths it'd be nicer to see scrolling "bars" of a sine wave, you have have n_xvals for 1 period, increase the start x_val on each new frame, and just test that the image looks correct based on the current frame number.

[kushalkolar]

@clewis7 verify that sine wave is correct based on frame index (if even or odd)