emphasize group name conventions

[westram]

The following conventions for names of taxonomic groups are/shallBe used in arb databases.

Some characters are problematic

character	problem	implemented behavior
_	used for groups combining multiple taxonomic ranks like in Ordername_Familyname	warn-on-write since [19278]
~	used when a taxon is "spread" across the . In that case the taxonname may occur in an enumerated flavour like TaxonXXX TaxonXXX~1 TaxonXXX~2 …	warn-on-write since [19278]
/	used by taxonomy() ACI-command. Display in may be confusing when group names contain slashes.	warn-on-write since [17110]
;	used in "tax…" entries to separate groups	warn-on-write since [19278]
!	used as prefix for keeled groups ⇒ shall not occur at beginning of groupnames	error-on-write since [17110]

Needed fixes:

• extend ACI command taxonomy to accept a 3rd parameter to specify the separator to use, e.g. taxonomy(100,";")
• predefined ACIs for generating tax entries shall
  • use new taxonomy parameter to directly create ';'-separated tax-entries
  • translate _ → ;
  • remove enumerated suffixes
• review parts of arb which auto-generate group names
  • make sure their defaults follow the above conventions:
    • group name modifications performed by ​Move groups.. (see also predefined config "report2name")
    • group names generated by ​Cluster detection fixed by [19283]
    • group names generated/assumed by predefined configs in ​Search taxonomic groups
  • do not notify about violation of group naming convention for each of e.g. 100 generated groups.
    Instead collect all and maybe show the first three warnings or so. implemented with [19277].
• implement #833 (generate taxonomic groups from tax…-entries)

[westram]

arb now complains about "unwanted" group names using the following messages:

• will interfere with taxonomy when ; or / are used.
• reserved for overlapping groups when _ is used.
• reserved for splitted groups when ~NUM (e.g. ~13) is used at end of name.