added pre-load functioanlity to data source, transmue.chainsolve now 200x faster.
made using temperature as part of the data source key optional.
rm'd temp flag from NullDataSource
more flags for not using temperature on data sources
Updated MCNP homepage URL.
Merge pull request #174 from cbrachem/staging

Updated MCNP homepage URL.
Merge pull request #173 from scopatz/enquicken

added pre-load functioanlity to data source, transmue.chainsolve now 200x faster
Merge branch 'staging' of github.com:pyne/pyne into staging