tests hang

This is related to #95 - don't think it is fixed:

(v1.3) pkg> st
    Status `~/.julia/environments/v1.3/Project.toml`
  [537997a7] AbstractPlotting v0.9.15
  [28f2ccd6] ApproxFun v0.11.8
  [c52e3926] Atom v0.11.3
  [6e4b80f9] BenchmarkTools v0.4.3
  [159f3aea] Cairo v1.0.1
  [35d6a980] ColorSchemes v3.5.0
  [5ae59095] Colors v0.9.6
  [861a8166] Combinatorics v1.0.0
  [a81c6b42] Compose v0.8.0
  [8f4d0f93] Conda v1.3.0
  [0c46a032] DifferentialEquations v6.9.0
  [31c24e10] Distributions v0.21.11
  [e30172f5] Documenter v0.24.3
  [7a1cc6ca] FFTW v1.2.0
  [442a2c76] FastGaussQuadrature v0.4.1
  [057dd010] FastTransforms v0.8.1
  [186bb1d3] Fontconfig v0.3.0
  [f013a474] FourierGPE v0.1.0 #master (https://github.com/AshtonSBradley/FourierGPE.jl.git)
  [92c85e6c] GSL v0.6.0
  [19dc6840] HCubature v1.4.0
  [7073ff75] IJulia v1.20.2
  [6218d12a] ImageMagick v1.1.0
  [916415d5] Images v0.19.2
  [c601a237] Interact v0.10.3
  [a98d9a8b] Interpolations v0.12.5
  [8197267c] IntervalSets v0.3.2
  [c8e1da08] IterTools v1.3.0
  [033835bb] JLD2 v0.1.10
  [e5e0dc1b] Juno v0.7.2
  [b964fa9f] LaTeXStrings v1.0.3
  [33e6dc65] MKL v0.1.0 #master (https://github.com/JuliaComputing/MKL.jl)
  [ee78f7c6] Makie v0.9.5
  [5a521ce4] MakieLayout v0.2.2
  [a3a9e032] NIfTI v0.4.0
  [3b7a836e] PGFPlots v3.2.0
  [8314cec4] PGFPlotsX v1.2.0
  [dd1b0cdc] PGPE v0.1.0 #master (https://github.com/AshtonSBradley/PGPE.jl.git)
  [d96e819e] Parameters v0.12.0
  [0e21426a] PhaseSpaceTools v0.1.0 #master (https://github.com/AshtonSBradley/PhaseSpaceTools.jl.git)
  [91a5bcdd] Plots v0.28.4
  [27ebfcd6] Primes v0.4.0
  [438e738f] PyCall v1.91.2
  [1fd47b50] QuadGK v2.3.1
  [6e0679c1] QuantumOptics v0.7.0
  [71555da5] Reel v1.1.1
  [295af30f] Revise v2.5.0
  [92719e2c] SPGPE v0.1.0 #master (https://github.com/AshtonSBradley/SPGPE.jl.git)
  [276daf66] SpecialFunctions v0.9.0
  [2913bbd2] StatsBase v0.32.0
  [24249f21] SymPy v1.0.10
  [37f6aa50] TikzPictures v3.0.5
  [28d57a85] Transducers v0.4.7
  [b688e990] VortexDistributions v0.0.0 #master (https://github.com/AshtonSBradley/VortexDistributions.jl.git)
  [44d3d7a6] Weave v0.9.1
  [0f1e0344] WebIO v0.8.13
  [c4c688b2] jlpkg v1.1.2

julia> versioninfo()
Julia Version 1.3.0
Commit 46ce4d7933 (2019-11-26 06:09 UTC)
Platform Info:
  OS: macOS (x86_64-apple-darwin19.0.0)
  CPU: Intel(R) Core(TM) i5-8259U CPU @ 2.30GHz
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-6.0.1 (ORCJIT, skylake)
Environment:
  JULIA_NUM_THREADS = 4

Start by reviewing issue #95 and reproducing the hang with the reported Julia 1.3 environment and package versions. The issue does not name a test file or entry point; done means identifying the cause of the hanging tests and confirming that the relevant test run completes.