Disable HotImport in PRODUCTION Environment

[huan]

the hotImport from module hot-import will enable us to automatically reload listeners of Wechaty.

Should be automatically disabled if process.env.NODE_ENV === 'production'.

See:

https://github.com/Chatie/wechaty/blob/dd2238de97cf349d8349aca10d1975600fd819e6/src/wechaty.ts#L365-L372

[xinbenlv]

Should the WeChaty provide this feature out of box or should it be configurable and overridable by the user?

[huan]

My opinion is to provide this feature out of the box.

And if process.env.NODE_ENV === 'production', then we should disable all the watchers inside hotImport because it should be not necessary and will cost some CPU circles.

The solution is to call hotImport() with the second parameter watch = false, like: hotImport(absoluteFilename, false).

[huan]

Fixed by the latest commit.