renamed .hgignore to .gitignore
adjustment of makeversion-script for git
added README.md file for GitHub project introduction
added old_hg_log.txt for manually mapping hg-rev numbers to git rev numbers
improved misc/makeversion to generate version numbers now in form YY.MMrevNMON-SH

where YY is Year, MM is Month, NMON is the commit Number in this month and SH ist the short form of the hash value