Add strategy for Pdb data

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https://en.wikipedia.org/wiki/Protein_Data_Bank_(file_format)

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To generate PDB files, we need functions to generate the following record types (ftp://ftp.wwpdb.org/pub/pdb/doc/format_descriptions/Format_v33_A4.pdf):

• [x] HEADER
• [x] OBSLTE
• [x] TITLE
• [x] SPLIT
• [x] CAVEAT
• [x] COMPND
• [ ] SOURCE
• [ ] KEYWDS
• [ ] EXPDATA
• [ ] NUMMDL
• [ ] MDLTYP
• [ ] AUTHOR
• [ ] REVDAT
• [ ] SPRSDE
• [ ] JRNL
• [ ] REMARK 0
• [ ] REMARK 1
• [ ] REMARK 2
• [ ] REMARK 3
• [ ] REMARK N
• [ ] DBREF
• [ ] DBREF1/DBREF2
• [ ] SEQADV
• [ ] SEQRES
• [ ] MODRES
• [ ] HET
• [ ] HETNAM
• [ ] HETSYN
• [ ] FORMUL
• [ ] HELIX
• [ ] SHEET
• [ ] SSBND
• [ ] LINK
• [ ] CISPEP
• [ ] SITE
• [ ] CRYST1
• [ ] ORIGX1 ORIGX2 ORIGX3
• [ ] SCALE1 SCALE2 SCALE3
• [ ] MTRIX1 MTRIX2 MTRIX3
• [ ] MODEL
• [ ] ATOM
• [ ] ANISOU
• [ ] TER
• [ ] HETATM
• [ ] ENDMDL
• [ ] CONECT
• [ ] MASTER
• [ ] END