Move reading of R-process data to inputs member function

The R-process data was tidied into the writing of the EPS file, and
the file was read twice. Reading is now in it's own member function
so is independent of file type. It is also stored in a vector of
pairs which can be accessed the second time the data is needed, in
the case oe an EPS file, rather than re-reading the file.
Tighten the scope of variables and remove calls to copy constructor.

If you use push_back on a vector, it has to be resized so the elements
that were in it originally are copied to a new location. By getting
the file size (number of lines) and reserving the space for the vector,
we avoid these copies.
Speed up reading and recording of user defined nuclei.

There is no need to store the values specified in the user file, so
as with reading the AME, store info in temp variables then find
appropriate isotope in the 'main' vector and toggle it's value.
Was reserving too much space by counting file size and not number of lines.