Improving text output for the help summaries
Replaced the wrong use of StringFlag with the more appropriated BoolFlag Type (Documentation of pkg cli is confusing on this topic)
small fix
Added -f option
(doc) Add document outlining preferred contribution method
Epic refactor commit in preparation for differential push
Added 'addm' to the cli

- Improved sanitization of the interactive input
- Moved some duplicated code into utils.go
- added support for Environment Variables TODOTXT_DATE_ON_ADD and TODOTXT_FORCE
small fixes
Fix help for the 'env' command and small fixes
Refactor commands initialization
Refactor name funcs and vars of Utils using idiomatic Go style