Adding a changelog to help people understand what's been fixed
Fixed an error in the left hand terms conduction terms

While revising the equations for one dimensional heat transfer (see #53), I recognized that
there was an error in the equations in these models.  One term included the effects of
length while the other didn't.
Fixing mistakes in the equations

I also rearranged these equations a little bit to make them clearer.

This closes #53.
Added resolution of #53
Merge branch 'master' of github.com:xogeny/ModelicaBook