read_rw included. read_rw reads ms1.dat and pbp.dat

doc updated + minor redefinition

input xdata Array{Real}

read_ms now returns YData
comp_t0 computes t0 R!=1 + rwf

Computes matching in the charm sector 
Scaling + chiral extrapolations are missing

functions returns uwreal not a Vector{uwreal}

meff takes the absolute value of the correlator.
plots now include mu values

find_xmin to be tested (issues with double exponential fits)