mcmc_param_check: MCMC parameter table check
In jameshay218/mcmcJH: Generic random walk MCMC algorithm for parameter inference

Takes the table of parameters for MCMC and checks for any invalid inputs. Table should have the following columns:

iterations: numeric value for the number of iterations in the MCMC algorithm
opt_freq: numeric value, specifying that the step sizes should be adapted every opt_freq iterations
thin: numeric thinning value for the MCMC chain
burnin: numeric value specifying the number of iterations to be discarded as burnin. Note that this is in addition to the adaptive period
adaptive_period: numeric value specifying the number of iterations to be discarded as the adpative period (ie. adapting step size)
nchain: number of chains to be run
save_results: currently does not have a use, but would take a value 1 or 0 to represent boolean value
likelihood_function: this should be a string that matches the name of a function available in the R environment. See the cost_functions documentation for details. Basically, this should be a function that takes the vector of parameters to be evaluated, the data to be evaluated against, the parameter table, the optimisation direction (ie. negative or positive log likelihood), and a function pointer for the model function to be evaluated
model_function: this should be a strnig that matches the name of a function in the R environment. This function will take a vector of parameters and a vector of time points, and will return the evaluated model results
lower_plot_bound: numeric value specifying the lower y bound for the model plot
upper_plot_bound: numeric value specifying the upper y bound for the model plot