cleanup

- update the documentation
- switch to Markdown format
- move the development documentation to devel-doc subpackage
remove '$Id$' tags

(not expanded by Git)
added .gitignore
fixed a compile warning

"warning: deprecated conversion from string constant to 'char*'"
resolved doxygen errors/warnings
- 2.24.0
Merge pull request #1 from yast/cleanup

Cleanup