Inline internal error list functions
Add separate error list column for syntax checker type

Makes the appearance of the syntax checker type customizable
[Fix #500] Merge branch 'colorized-checker-type'

* colorized-checker-type:
  Add separate error list column for syntax checker type
  Inline internal error list functions
Update credits and changelog [#500]
Document error list faces [#500]
Slightly refine credits
Remove dead reference
Rebuild Texinfo manual