This commit removes the usage of the boost preprocessor library to
iteratively generate templates with a variable number of parameters. It
is replaced with a template that is expanded by running it through the
pyexpander macro processing tool (http://pyexpander.sourceforge.net).

One reason for this change is to make the code easier to read. In
particular, it is difficult to understand compiler errors when they
occur deep within an iterating macro. Another reason for this change is
that the Intel compiler currently has a bug that breaks with the boost
preprocessor library.

One issue with this approach is that the macro expansion is not part of
the build process. Although open, pyexpander is not a tool most
developers will have readily installed on their system. Thus, if you
want to make changes to any of the macro code, you have to make sure
pyexpander is installed, then make changes to the input files, then
manually run pyexpander from the command line.