Changes in behaviour of suggestion popup

[avasid]

A few changes that I would suggest,

1. The first option should be in focus by default.
2. Navigating the options doesn't change the main code, rather the ENTER key would implement the code as well as close the window.
3. Because the ENTER key's function is now inserting code, ESC key should be used to close the suggestion box.

I suggest these changes because they seem more natural and inline with other mainstream IDEs.

I have implemented all above mentioned changes along with fixing some typos. If you allow, I would open a pull request for the merge.

[wenmin-wu]

Cool, man. Please open a pull request and then I can do some test