Employing checkmate package and Changing file names of vignettes

1 Employing checkmate package

I decided to employ checkmate pacakge.

The package enables us to check arguments of function easily.

Employing the package doesn’t affect the users of imagerExtra greatly.

However, the package solved my problem with checking function arguments.

Now, there is nothing to hinder my implementing of new function.

1.1 Changes of checking function arguments

Changes that affect the users of imagerExtra are listed below.

I should not change the way of checking function arguments without thinking.

That’s why I wrote the reasons of the changes.

EqualizeDP function returns a error instead of a warning when t_down is bigger than t_up.

t_down must be smaller than or equal to t_up.

I believe t_down that is bigger than t_up is a result of a mistake.

Functions that have range argument returns a error instead of warning if range isn’t ascending order.

I believe range that is not ascending order is a result of a mistake.

ocr function and ocr_data function of tesseract package accept color image.

OCR function and OCR_data function should accept color image because there is no reason to reject color image.

I renamed the file names of the vignettes because those were too long.