Merged Conceal Message Timestamp Module

- Module renamed to "Readable Dates and Concealed Times Module".
- Functions of the "Conceal Message Timestamp Module" included.
Formatting
date and times in two separate modules didn't work well.
- Fixed formatting for the announcement module.
- README extended (license, module settings, language support,
dependencies
and GitHub link added).
- Performance improvements.
- Sanity checks added.
