Don't use 'show paren' mode because it corrupts the virtual indentation of Org mode.
Revert "Add faces for 'Rainbow-delimiters' mode."

This reverts commit 56024fe408a1035309ca8dd516a837cacbe4375b.

This is because I'm not satisfied with the mode and the faces.
Configure the colors for highlight-parentheses.
Add the 'highlight-parentheses' package.