- change pflags back to spf13

- fix more bugs related to ToStr of list types

fix a bug that caused shorthand name for slice doesn't get generated

add tags for shell completion method

update example link in README.md

fix a bug that cause usage doesn't show when there is no sub-command …

…and there is no root method

add ExecuteCMDPath

Merge pull request #419 from spf13/ci

add github actions

rename branch to v2

some clean up

add withRootMethod

update README.md

fix a bug on getNextActPosState() in case of having bool arg