case-sensitive search and uppercase/lowercase matching.

Hi, adding c before a shortcode capitalizes the first letter. For example [cmonth]. See: https://gauravtiwari.org/snippet/dynamic-month-year/#:~:text=Capitalize%20month%20names

About the complete uppercase, this should be done with CSS. Add some class surrounding the shortcode and use .class {text-transform:uppercase;}

Please see: https://developer.mozilla.org/en-US/docs/Web/CSS/Reference/Properties/text-transform

Thank you so much for the review.