Fix checkbox width in product data meta box
Merge pull request #4363 from emzo/product-data-checkboxes

[2.1-beta-2] Fix checkbox width in product data meta box
data tabs tweaks
color tweaks
Only allow a fee to be added once
Credit card form actions - start and end
tooltips on variations not showing after using link all variations button Fixes #4366
Fixing method call in verify_nonce function
Downloadable File Fixes/Tweaks

* Hooked up new downloadable product permissions function to
completed/processing actions
* WC_Product::get_files() is used rather than the underlying
_downloadable_files meta directly
* $this is passed to downloadable product filters in WC_Product in place
of $this->id which doesn't does not afford you the particular variation
when a product variation is being used.
Expiry date calculation based on order completion date
Add coupon code placeholder to cart template
Revert back to ob_end_clean to fix errors

ob_clean does not turn off output buffering as ob_end_clean does. On
some hosts ob_clean results in an error like: transfer closed with 3
bytes remaining to read. ob_end_clean fixes this.
Fix HTTP_X_FORWARDED_HOST notice
Merge pull request #4381 from ChuckMac/master

Fixing method call in verify_nonce function
Merge pull request #4406 from maxrice/master

Fix HTTP_X_FORWARDED_HOST notice
Merge pull request #4401 from toddlahman/master

Revert back to ob_end_clean to fix errors
Merge pull request #4386 from justinstern/master

Downloadable File Fixes/Tweaks
Merge pull request #4388 from niravmehta/master

Expiry date calculation based on order completion date
Merge pull request #4330 from kloon/tweak_file_title_download_permissions

Tweak file title download permissions
Merge pull request #4305 from helgatheviking/feature/min_max_args

add $min_or_max and $display params to variation pricing functions