Fix various problems with manual examples

[fingolfin]

Overall there are many more places where the output shown in the manual examples does not match reality.

Ideally, they would match, and then the manual examples would be run as part of the CI tests. That would serve two purposes: ensure that the manual examples are working, and that the recorded output matches reality.

Right now, many examples fail; but this patch reduces that at least a bit, and ensures that those test at least terminate. You can run the manual tests by entering gap makedoc.g tst/testall.g which first builds the manual which extracts the manual examples, and then runs the enlarged test suite.

Of the remaining failures, the main categories are:

• some examples involve randomness: random elements random codes. We could try to work around this by initializing the RNG to a specific state at the start of tst/testall.g
• some examples include comments in the "expected outputs", which throws off the code which compares the expected against actual outputs
  • this can be fixed by adjusting the examples, moving the comments around a bit
  • alternatively one could write a custom compare functions to be passed to TestDirectory which ignores those comments for us. Probably not worth the effort, though
• polynomials are printed "in the wrong order": e.g. the examples show x_1+Z(2)^0 but GAP actually prints x_1+Z(2)^0 or x+Z(2)^0.
  • I already fixed some of these in this PR
  • in many cases, it might actually be best to just not print the polynomials...

[codecov[bot]]

Codecov Report

Merging #80 (d1fbef7) into master (e1eb3d0) will not change coverage. The diff coverage is n/a.

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  Branches      203      203           
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  Hits         7242     7242           
  Misses       7426     7426