added alias to code generator. not using them
fixed namespace aliasing
removed comment
added Contains method to matquery.
rm'd comments
added default constructor for arcs for usage as values in maps
Added a warning to the constructor
Merge pull request #800 from scopatz/nsalias

Namespace aliases in pp
Merge branch 'def-arc' of https://github.com/gidden/cyclus into gidden-def-arc