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.
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
Add  array to woocommerce_downloadable_file_permission_format
Merge pull request #3825 from ragulka/file-permissions-format-filter-data

Add $data array to woocommerce_downloadable_file_permission_format
Wrong checked var