- check for div by zero error, patch suggested by Daniel Cegielka

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/blotter@1635 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
- change version mechanism to major.minor.svnrev to match PerfA and quantstrat

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/blotter@1636 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
- divide by zero checks for implausibly perfect systems suggested by Daniel Cegielka

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/blotter@1637 edb9625f-4e0d-4859-8d74-9fd3b1da38cb