Document indexing strategies

[benjaminhwilliams]

Provide PHIL help for each of the basis vector and lattice search strategies and pass these through to the dials.index PHIL scope. Give a little more info on how each strategy works in the docstring of the corresponding class.

[codecov]

Codecov Report

Merging #1519 (4dd12f9) into master (b36efe5) will increase coverage by 0.00%.
The diff coverage is 100.00%.

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  Lines       68965    68970    +5     
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+ Hits        45257    45261    +4     
- Misses      21866    21867    +1     
  Partials     1842     1842           

[rjgildea]

Thanks for adding these, I'm sure users will find the additional help strings useful.

As well as being untidy, I'm not convinced the extra whitespace padding and single quotes in the phil_help attributes are even necessary - the following still appears to work:

libtbx.phil.parse("""
%s
.expert_level=1
.help=%s
{}
""" % (entry_point.name, entry_point.load().phil_help[2:-2])).show(attributes_level=1)

fft1d
  .help = "Search for the basis vectors of the direct lattice by performing a"
          "series of 1D FFTs along various directions in reciprocal space."
          "This has a lower memory requirement than a single 3D FFT (the fft3d"
          "method). This method may also be more appropriate than a 3D FFT if"
          "the reflections are from narrow wedges of rotation data or from"
          "stills data."
{
}

i.e. I think we can safely remove the whitespace padding and extra single quotes and it will still work. The default Strategy.phil_help could also be phil_help = None which seems cleaner and more Pythonic.

[dagewa]

Looks good to me. I added one suggestion for the low res spot match help.

[benjaminhwilliams]

As well as being untidy, I'm not convinced the extra whitespace padding and single quotes in the phil_help attributes are even necessary

The default Strategy.phil_help could also be phil_help = None which seems cleaner and more Pythonic.

Oh brilliant, I approve. I thought I tried this in tinkering with PHIL but I clearly did something else wrong and convinced myself it was because I was passing None or because I hadn't properly quoted the help string. Every time I try to use PHIL, I use it wrong somehow, so I can never work out what the rules are.