Dhurba baral

fixes #73 `@params` was used in many places but it was not initialized so, I checked the previous [tag](https://github.com/raul/pt/blob/v1.0.2/lib/ptt/ui.rb#L20) and added this line here.

fixes #80 According to ruby 2.7 [release documentation](https://www.ruby-lang.org/en/news/2019/12/25/ruby-2-7-0-released/) `Module#name`, `true.to_s`, `false.to_s`, and `nil.to_s` now always return a frozen String. The returned String is always the same for a given object....

FrozenError: can't modify frozen String: ""

1

I'm getting following exception from ruby `2.7.2` ``` Please select the project for the current directory (1-1, 'q' to exit) 1 Thanks! I'm saving this project's info in /Users/dhurba/code/random/pt/.pt: remember...