plot_mc_acceptance: Plot Metropolis coupling acceptance rates
In bobverity/rmaverick: Analysis of population structure

Plot Metropolis coupling acceptance rates between all adjacent rungs. It is important that acceptance rates are greater than zero between all pairs of rungs in order to give confidence that the MCMC has thoroughly explored the full posterior distribution. If there are any points in this plot where acceptance rates drop close to zero then consider changing the number of rungs or their distribution (see rungs and GTI_pow arguments in run_mcmc(), respectively).

1	plot_mc_acceptance(proj, K = NULL, x_axis_type = 1)

`proj`	an rmaverick project, as produced by the function `mavproject()`
`K`	which value of K to produce the plot for
`x_axis_type`	how to format the x-axis. 1 = integer rungs, 2 = values of the thermodynamic power.