Merge pull request #3591 from Gator92/tax_rate_foreign_key

Adds an index to the foreign key in table woocommerce_tax_rate_locations
Merge pull request #3576 from rnt/master

Fixing warnings with 'strict standarts' and file permission
Rupee Closes #3529
Use version_compare to check for required jQuery. Closes #3567
Addons page Closes #3331
Min
Remove old extension prompt
Removed hooks and functions from admin.
Move return class after class definition. Fixes PHP 5.5 fatal errors.
Fix result count display when posts_per_page is set to -1

When your posts_per_page is set to -1 the display is output as `Showing 1–-1 of 15 results` when displaying all items when it would be better to show `Showing all 15 results`
Let hooks know if email is plain text
Make sure end( gets a variable to work around strict notices
Strict notice fix for get_price_html implementation
adding WPLANG to system status
Change bulk edit stock quantity field type to number
Change product quick edit stock quantity field type to number
Add woocommerce_product_quick_edit_start and woocommerce_product_quick_edit_end hooks
Update user meta for billing fields
Sortable is needed for admin scripts
Typecast array