This commit doesn't change any code. Only the doxygen related
documentation has been updated. The warning levels from doxygen
have been increased, so that undocumented parameters now cause
a warning to be issued.
This commit eliminates these warning messages.
I upped the warning levels within doxygen and then filled in
the missing information within the currently covered files.
I also created a few more doxygen modules, aiming towards getting
100% coverage of classes within at least one doxygen module.
My hope here is to start adding doxygen documentation
for the strong electrolyte thermodynamics in the near future.
