B_OK here when called with an empty string.
Since this is the natural thing to expect anyway, I changed our version to return
a sane value here as well - if this causes an error within our StyledEdit, as
shatty writes, we should just fix our StyledEdit.
Cleanup to match our style guides a bit better, added license.
git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@16328 a95241bf-73f2-0310-859d-f6bbb57e9c96