coef_plot: Fix naming for non-lm fits

- The default mode (with no coef.names) was only working for lm fits
- Now a coefficient column must be passed to .coef_plot
coef_plot: Add renaming example
coef_plot: .coef.names and .coef.order

- These functions replace some functionality within
.coef_plot that may be re-used by other methods
coef_plot: Add coef_catseye

- The cats eye plot may be useful for MCMC regressions
Merge remote-tracking branch 'origin/master'