Fix bugs identified by user

[mducle]

C. Balz contacted me with some bugs - specifically relating to tutorials 12 and 35:

• The syntax for disp2sqw_eval in Horace has changed and needs a flag '-all' at the end to compute the intensities, so we need to change the example in tutorial 12.
• In tutorial 35, a long-known bug is that the experiment points shift if you resize the figure because they are actually 'circles' plotted on the canvas coordinates rather than the data coordinates. There are two work arounds which should be documented. - Fixed on webpage already
• Finally, also related to tutorial 35 but not in the tutorial itself - sw_plotspec has the option to overplot data (like fitspec does) but it assumes that the column names are En#, I#, and s# whereas fitspec ignores the names and just uses the column ordering - but the example file LuVO3_fitted_modes.txt calls the final column sigma# rather than s# so sw_plotspec fails when given it as input.

[github-actions]

Test Results

    4 files  ±0    124 suites  ±0   5m 26s ⏱️ +27s
  832 tests ±0    814 ✅ ±0  18 💤 ±0  0 ❌ ±0 
2 328 runs  ±0  2 292 ✅ ±0  36 💤 ±0  0 ❌ ±0 

Results for commit 84529bc. ± Comparison against base commit eacac5a.

This pull request removes 2 and adds 2 tests. Note that renamed tests count towards both.

sw_tests.unit_tests.unittest_ndbase_optimisers ‑ test_optimise_rosen_parameter_fixed_minimum_not_accessible_with(optimiser=@ndbase.lm4)
sw_tests.unit_tests.unittest_ndbase_optimisers ‑ test_optimise_rosen_parameter_fixed_minimum_not_accessible_with(optimiser=@ndbase.simplex)

sw_tests.unit_tests.unittest_ndbase_optimisers ‑ test_optimise_rosen_parameter_fixed_minimum_not_accessible_with_vary_arg(optimiser=@ndbase.lm4)
sw_tests.unit_tests.unittest_ndbase_optimisers ‑ test_optimise_rosen_parameter_fixed_minimum_not_accessible_with_vary_arg(optimiser=@ndbase.simplex)

[RichardWaiteSTFC]

Changes look good, thanks!

I did have a quick test of tutorial 35 with the file attached in this PR - fitspec produced this

which agrees with
https://spinw.org/tutorials/35tutorial