Migrate from nsf/gocode to mdempsky/gocode for completion results

[Frederik Ring (m90)]

As package nsf/gocode is unmaintaned this is now consuming mdempsky/gocode.
In order to cater for changes, correctly handle empty results and promise
rejections.

This would solve #1645 although for reasons unclear to me, the updated gocode package will not provide any results for members of unimported packages (hence the skipped test case). Don't know if this is a dealbreaker or can be fixed deeper down in goSuggest.ts.

[Frederik Ring (m90)]

Scrap the comment about the test that needs to be skipped, that was an issue I encountered locally as math can actually be an ambiguous package (there is github.com/gohugoio/hugo/tpl/math) and the extension therefore decides to not display anything here: https://github.com/Microsoft/vscode-go/blob/5bc4ce40557a044cd790b9941271908b9135bc68/src/goSuggest.ts#L361-L363

[Ramya Rao (ramya-rao-a)]

Awesome, Thanks!

[Frederik Ring (m90)]

Ramya Rao (@ramya-rao-a) Should we also already update the parts of the wiki (this and this) that still point to the nsf gocode or should that wait until it has actually been released?

[Ramya Rao (ramya-rao-a)]

Frederik Ring (@m90) Let's wait until the release for the wiki update.

I was wondering if we should prompt the users using Go 1.10 and above to update their gocode if the current one panics. Because otherwise, this change will only help first time installs and those who already have go get the new gocode

[Frederik Ring (m90)]

From what I understand the mdempsky gocode should work fine on older supported Go versions as well, so ideally a prompt like this would show up for everyone.

Unfortunately I have a hard time coming up with an idea on how to know which gocode is installed on a user's machine as the binary name is the same and it will also be installed into $GOPATH/bin. It looks like the nsf gocode prints slightly different output on gocode -h, but I'm not too sure if this is the most robust way of doing it.

[Ramya Rao (ramya-rao-a)]

Ok, In that case, we can leave it as is.
I can update the FAQ to include a note on this.