Added spacegroup synonyms, for interpreting user input names

[rhfogh]

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[rhfogh]

Note

1. 'synonyms' is a new field, so it can break nothing

2. Space group names and synonyms follow CCP4 v9 symop.lib, with or without internal spacings, with the following additions:

SG3 'P 2'
SG4 'P 21'
SG5 'C 2
SG6 'P m'
SG7 'P c'
SG8 'C m'
SG9 'C c'
SG10 'P 2/m'
SG11 'P 21/m'
SG12 'C 2/m'
SG13 'P 2/c'
SG14 'P 21/c'
SG15 'C 2/c'
SG17 'P2212', 'P 2 21 2', 'P2122', 'P 21 2 2'
SG18 'P21221', 'P 21 2 21', 'P22121', 'P 2 21 21'

Note: For SG17 and SG18 these are alternate settins, but they are treated as synonyms

R versus H names:

Space groups 146, 148, 155, 160, 161, 166, and 167
are given names starting with 'R'. Name versions starting with 'H' are treated as synonyms.
No distinction is made at the name/synonym level between rhombohedral and hexagonal settings