error_plot: Graph performance of ensemble of regression models
In seniorburito/ensemble:

When given training predictors, training responses, and predictors, responses this function outputs a plot mean squire errors of the models The models used for this ensemble are: KNN, Random forest, LASSO, Ridge and linear

1	error_plot(X_train, y_train, X_test, y_test, rfntree, KNNk, rfmtry, doKNN)

`X_train`	training predictor vector
`y_train`	training response vector
`X_test`	predictor vector
`y_test`	responses vector
`rfntree`	number of trees to grow. This should not be set to too small a number. Set to 100 by default
`KNNk`	Number of neighbours considered it KNN, set to 5 if unspecified
`rfmtry`	Number of variables randomly sampled as candidates at each split in random forest. Set to 6 by default
`doKNN`	Whether to run KNN or not, TRUE by default