Restructure 'file_paths' to allow for names (Closes #3320) etc. For #2765.

@coenjacobs @justinstern @maxrice These are major changes - CC ing you
guys in to take a quick look through. I know some extensions such as
vouchers will be affected.
Don't display shipping address if shipping is disabled
Hide shipping address if shipping is disabled
Hide shipping address if shipping is disabled
Allow variations JS to be used on multiple products in the same form
POT update
es_ES update
Simpler tax rate check which Closes #3813

Could do with some more testing @ChromeOrange, and applying to .15 if
ok @coen
Merge branch 'downloadable-files-2.1'

Conflicts:
	assets/css/admin.css
Set session when removing last item. Closes #3739
Pass args to variation forms from cart page. Closes #3568
Merge pull request #3818 from rnt/master

Base pot update & es_ES po update
Merge pull request #3815 from pmgarman/master

Don't display shipping address if shipping is disabled
Merge pull request #3817 from franticpsyx/variations_js_form

Allow variations JS to be used on multiple products in the same form
minify #3817
Option for itemized vs grouped taxes. Closes #3453.
standard should be blank. Closes #3799.

@coenjacobs .15
Round price adjustments. Closes #3797.
Include a link to admin. Closes #3796
Use get_the_title() instead of $post->title, because there could be 'the_title' filters