remove autogen dependency

This series removes dependency on GNU AutoGen for handling options and configuration files. The initial one-off conversion from AutoGen definitions to JSON is done with parse-autogen program.

Fixes: #773 (closed), #774 (closed), #775 (closed)

• replace command line option handling with getopt (#775 (closed))
• replace template file parsing with minimal parser (#774 (closed))
• texinfo generation (#773 (closed))
• man pages generation (#773 (closed))

Checklist

• Commits have Signed-off-by: with name/author being identical to the commit author
• Code modified for feature
• Test suite updated with functionality tests
• Test suite updated with negative tests
• Documentation updated / NEWS entry present (for non-trivial changes)
• CI timeout is 2h or higher (see Settings/CICD/General pipelines/Timeout)

Reviewer's checklist:

• Any issues marked for closing are addressed
• There is a test suite reasonably covering new functionality or modifications
• Function naming, parameters, return values, types, etc., are consistent and according to CONTRIBUTION.md
• This feature/change has adequate documentation added
• No obvious mistakes in the code