revised incr() function to be much faster
added model for age-specific incidence to be calculated based on FOI matrix
age / time independent version, results for Oxford meeting on 8 Sept 2014
added EPP files

Implements EPP r-spline model.
moved all parameters to a list argument (R version)
changed ts.epi.start to index rather than calendar time
changed sex ratio at birth (SRB) to be M/F instead of 100*M/F
update C implementation to use argument list

This is done by updating parameters.h and parameters.c, and adding a
function in rlib.cpp to read R list of fixed parameters. Memory is
allocated dynamically for time-varying parameters to allow for
differing projection durations (parameters.c).

ART initiation is revised to use sex-specific numbers on ART.

Adds test-spectrum.R to show that R and C implementation give the same
outputs.

removes C++/functions.R: C code calls has been moved to R function.

TODO: this breaks test.cpp, and breaks force of infection matrix (rmat)
model version.

TODO: passing param and fp (fixed params) as separate arguments is a
bit silly — revise this in a future development.