Nasa polynomials

Here is the thermo PR.

I'm not fully happy with the thermo, but I'm not sure how exactly a nice general thermo module should look like.  To start with the not very nice thing, cea and nasa polynomials have differerent expressions and the nasa can have custom temperature intervals.  So when the cea is fully described and only the coefficients are needed (thus one ```vector<CoeffType>``` needed in constructor), a nasa polynomials requires the temperatures and the coefficients (thus two ```vector<CoeffType>``` in constructor).  So nasa and cea have the two constructors for compatibility.  There is thus a default for the temperature interval for the nasa polynomials, and a very ineleguant constructor for the cea, only for compatibility purposes.

The test has been extended also to test for all thermo quantities.