fix external terminal launching on mac(darwin)

[LazyRen]

Hi, First of all, thanks for such a great extension.
As #28 mentioned, original extension does not allow me to use external terminal for the mac Terminal.

I had some osascript that I previously used for Sublime Text, so I gave it a shot for myself.

It works fine for my installed extension even tho it is not the best solution.(using delay command and such..)

Hope this helps!

p.s.
For the extension I installed, it uses term ${file.$directory},
but forked one uses ${file.directory}. I did changed in this way, but not sure this is the right way.

[danielpinto8zz6]

hi,
thanks