Add ID subfield to VCF v4.3 test file's structured header

In VCF v4.3 structured meta-information lines must have an ID subfield.
Split the value into identifier-like ID and text Description subfields
to demonstrate the structured benefit, though for a non-INFO/FORMAT/etc
line there's probably nothing requiring ID's value to be identifier-like.
Fixes #772.

This leaves the similar 4.1 and 4.2 files as is, as it is less clear
whether ID-less structured headers are merely discouraged there.

test/vcf/4.3/passed/complexfile_passed_000.vcf

@@ -41,7 +41,7 @@
 ##MYID=<ID=MINE,Number=1,Type=String,Description="Some random tag">
 ##MYID=<ID=MINE2,Number=1,Type=String,Description="Some random tag,with commas">
 ##AnalysisTitleQuotes="FINRISK: Whole-exome sequencing of Dietary, life style, and genetic determinants of obesity and metabolic syndrome (DILGOM)"
-##AnalysisTitleBrackets=<"FINRISK: Whole-exome sequencing of Dietary, life style, and genetic determinants of obesity and metabolic syndrome (DILGOM)">
+##AnalysisTitleStructured=<ID=FINRISK,Description="Whole-exome sequencing of Dietary, life style, and genetic determinants of obesity and metabolic syndrome (DILGOM)">
 ##AnalysisTitlePlain=FINRISK: Whole-exome sequencing of Dietary, life style, and genetic determinants of obesity and metabolic syndrome (DILGOM)
 ##source_20130015.4=vcf-annotate(r810) -c CHROM,POS,dbSNPmismatch,REF,ALT,- -a /nfs/users/nfs_p/pd3/sandbox/hapmap/dbSNP-b137/annots-rsIDs-dbSNPv137.2012-09-13.snp-indels.tab.gz -d key=INFO,ID=dbSNPmismatch,Number=0,Type=Flag,Description=The position in the dbSNP but alleles different -f /lustre/scratch106/projects/uk10k/BUILD/vrtrack_uk10k_cohort/REL-2012-06-02/calling/snps-indels/config/dbSNPmismatch.filt
 #CHROM POS ID REF ALT QUAL FILTER INFO FORMAT HG00096 HG00097 HG00099 HG00100 HG00101 HG00102 HG00103 HG00104 HG00106 HG00108 HG00109 HG00110 HG00111 HG00112 HG00113 HG00114 HG00116 HG00117 HG00118 HG00119 HG00120 HG00121 HG00122 HG00123 HG00124 HG00125 HG00126 HG00127 HG00128 HG00129 HG00130 HG00131 HG00133 HG00134 HG00135 HG00136 HG00137 HG00138 HG00139 HG00140 HG00141 HG00142 HG00143 HG00146 HG00148 HG00149 HG00150 HG00151 HG00152 HG00154 HG00155 HG00156 HG00158 HG00159 HG00160 HG00171 HG00173 HG00174 HG00176 HG00177 HG00178 HG00179 HG00180 HG00182 HG00183 HG00185 HG00186 HG00187 HG00188 HG00189 HG00190 HG00231 HG00232 HG00233 HG00234 HG00235 HG00236 HG00237 HG00238 HG00239 HG00240 HG00242 HG00243 HG00244 HG00245 HG00246 HG00247 HG00249 HG00250 HG00251 HG00252 HG00253 HG00254 HG00255 HG00256 HG00257 HG00258 HG00259 HG00260 HG00261