Use prettify() when saving database instead of toPrettyRepr().
Use prettify() when saving database instead of toPrettyRepr().

The toPrettyRepr() methods were removed from the kinetics classes to
avoid having multiple repr-like methods. The prettify() function
automatically provides functionality for converting repr() output to a
prettier (i.e. multi-line) version.

Probably we should move the prettify() function out of the rmgpy.cantherm
subpackage at some point, but that's for another commit.

comocheng/RMG-Py,nickvandewiele/RMG-Py,nyee/RMG-Py,enochd/RMG-Py,KEHANG/RMG-Py,chatelak/RMG-Py,pierrelb/RMG-Py,KEHANG/RMG-Py,pierrelb/RMG-Py,nyee/RMG-Py,chatelak/RMG-Py,enochd/RMG-Py,faribas/RMG-Py,comocheng/RMG-Py,faribas/RMG-Py,nickvandewiele/RMG-Py