More semantic checks for document comments

There are a couple of semantic checks that could be implemented:

• tags not applicable for the definition
  • functions
  • testcases
  • altsteps
  • simple data types
  • structured data types
  • components
  • ports
  • moduleparts
  • constants
  • templates
  • signatures
  • modules
  • groups
  • control parts
  • component local defs
• @param/@member tags for non-existing identifiers
• undocumented members/params