Added templates for modulated structure dictionary.

[jamesrhester]

These additional template blocks supplied by G Madariaga as part of modulated structure dictionary update.

[vaitkus]

Looks good overall.

However, additional semantic incompatibilities may become evident once these items are put to use in actual import statements.

[vaitkus]

The '7_645' example may be incompatible with the provided definition since the translation part consists of only 3 elements (p = 3).

The definition states that:

The number 'p' must agree with (_cell_modulation_dimension + 3). 

The _cell_modulation_dimension is currently defined to have values in the range of 1..8, thus leaving the minimal p value at 4.

Also, having an example with at least 4 translations would be useful to showcases the difference from the conventional 3D symmetry code data item.

[vaitkus]

The "used in calculating the angle" part here is probably a bit too specific. I assume that this save frame will also be imported by items that do not deal with angles, e.g. _geom_bond.site_ssg_symmetry_1.

[jamesrhester]

However, additional semantic incompatibilities may become evident once these items are put to use in actual import statements.

The corresponding dictionary updates are now available as a pull request.

[vaitkus]

Suggested change

	'.' 'no symmetry or translation to site'
	. 'no symmetry or translation to site'

[vaitkus]

The special value should not be quoted to distinguish it from a full stop. The same approach is taken in the 'site_symmetry' save frame.

[vaitkus]

Suggested change

	_enumeration.range 0:

[vaitkus]

The '_cell_wave_vector.seq_id' is defined as having the enumeration range of [0. +inf) therefore the same should extend to the linked items.

P.S.: Judging from the usage examples the enumeration range should most likely be [1; +inf) for all of these items, but this point can be addressed in a separate issue.