reduce test warnings due to jim, prompt

[JeffFessler]

The test suite was using MIRT.jim instead of MIRTjim.jim and that led to a lot of noisy warnings.
Likewise for prompt.
This PR has the tests mostly use the MIRTjim versions so that there are just a few warnings.

It also eliminates a no-longer-needed workaround related to the windows rm issue
#58

There are no changes to src/ except for comments, so no version bump.

[codecov]

Codecov Report

Merging #99 (d5e4017) into master (5166701) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #99   +/-   ##
=======================================
  Coverage   99.81%   99.81%           
=======================================
  Files          44       44           
  Lines        2172     2172           
=======================================
  Hits         2168     2168           
  Misses          4        4           

Impacted Files	Coverage Δ
src/fbp/image_geom.jl	100.00% <ø> (ø)

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