BUG: Need to include header <new> to use placement new syntax.  Really this should be fixed by replacing the stream buffer to set a new string instead of reconstructing the object, but this will require quite a bit of work to do portably.

ENH: Unified WriteDependRules, WriteBuildRules, WriteCleanRules, and the future WriteInstallRules into a single WritePassRules method.  Also added WriteTargetDependsRule and WriteTargetCleanRule methods to unify writing of depend and clean rules for each target.

ENH: Moved code that checks output path variables to separate ConfigureOutputPaths method.  Needed to provide access to the same code from a subclass.