[ctioga2] make abs(x) accessible

git-svn-id: svn+ssh://rubyforge.org/var/svn/ctioga2/trunk/ctioga2@496 86c91514-0d3b-42e0-aed1-4dfce116d947
[ctioga2] offer the possibility to log to a file rather than to the terminal (for the windows port in particular)

git-svn-id: svn+ssh://rubyforge.org/var/svn/ctioga2/trunk/ctioga2@497 86c91514-0d3b-42e0-aed1-4dfce116d947