Policy: double quote: allow if dollar in string

[tinmarino]

One line to allow double quotes if there is a dollar in the string.
As example from my vimrc:

let $h = expand($HOME)
let $w = expand("$h/wiki/wiki") | let $wiki = $w

Cleaner than $h . '/wiki/wiki' in my opignon

[coveralls]

Coverage decreased (-0.6%) to 95.452% when pulling 45951a5 on tinmarino:master into bcd6562 on Kuniwak:master.

[codecov-io]

Codecov Report

Merging #340 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #340   +/-   ##
=======================================
  Coverage   93.69%   93.69%           
=======================================
  Files         133      133           
  Lines        4155     4155           
  Branches      417      417           
=======================================
  Hits         3893     3893           
  Misses        167      167           
  Partials       95       95

[blueyed]

Thank you!

[tinmarino]

Well thank you. Awesome plugin (I'm using it with vim's ale) ! Fast merge, congrat.
Keep on linting !

[tyru]

@tinmarino
I don't have opinion about this policy. Just I want to question: do you know
expand("$h/wiki/wiki") and expand('$h/wiki/wiki') are the same result?

[tyru]

I don't have opinion about this policy

ah, wait.
this changes built-in (enabled by default) policy.

I think this change is unnecessary because above two expressions are evaluated to the same results.

[blueyed]

True, missed that.
Since expand('$HOME') also works it should also prefer single quotes there then I guess.
@tinmarino are we missing something, or do you agree this should be reverted?

[tinmarino]

Hi guys. Tk @tyru !!

Actually I was missing something. My PR is an error, my bad : the $ symbol do not get expanded even with double quote.

echo "$HOME"    " -> $HOME
echo '$HOME'    " -> $HOME

Sorry for that.