Clear cached inspector points on every redraw

[austin-schick]

Fixes a bug where inspector points wouldn't update to match the newest drawing.

[schmave]

Any idea when this broke?

[schmave]

Looks like the Windows tests are timing out on Appveyor and have been for a while. I took a look just now and the -zip versions are running in 2-3mins on Windows, but -pip takes 22 mins each. Maybe skip all but one *-pip on Windows?

*-pip are failing on mac, but presumably that's due to cairo.

[schmave]

Windows tests passed! For some reason test_image_gen is really slow when installed with pip:

py37-zip: OK (154.86=setup[10.20]+cmd[11.56,1.86,0.99,130.14,0.11] seconds)
  py38-zip: OK (142.67=setup[11.53]+cmd[10.30,2.38,0.94,117.42,0.11] seconds)
  py39-zip: OK (118.41=setup[12.02]+cmd[10.91,2.08,1.05,92.25,0.11] seconds)
  py310-pip: OK (1304.02=setup[11.86]+cmd[4.55,9.94,9.08,1268.50,0.09] seconds)

Many of the Mac tests passed:

  py36-pip: SKIP (5.88 seconds)
  py36-zip: SKIP (5.83 seconds)
  py37-pip: SKIP (0.02 seconds)
  py37-zip: SKIP (0.01 seconds)
  py38-zip: OK (166.21=setup[15.22]+cmd[11.40,3.94,1.42,134.18,0.04] seconds)
  py39-pip: FAIL code 1 (191.93=setup[16.42]+cmd[19.00,1.58,1.19,153.74] seconds)
  py39-zip: OK (156.66=setup[9.70]+cmd[7.90,2.53,0.91,135.54,0.08] seconds)
  py310-pip: FAIL code 1 (194.32=setup[9.71]+cmd[16.33,1.29,1.42,165.57] seconds)
  py310-zip: OK (213.18=setup[9.48]+cmd[8.42,3.53,1.53,190.18,0.05] seconds)
  py311-pip: FAIL code 1 (190.79=setup[10.85]+cmd[12.66,1.10,1.51,164.68] seconds)
  py311-zip: OK (159.58=setup[13.24]+cmd[9.08,1.51,1.16,134.54,0.05] seconds)