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
compare to lowercase class name
Merge pull request #3602 from BFTrick/add-lang-to-system-status

Adding WPLANG to System Status
Merge pull request #3607 from ragulka/product-quick-edit-hooks

Add product quick edit start & end action hooks
Merge pull request #3606 from ragulka/bulk-edit-field-type

Change quick/bulk edit stock quantity field type to number
Merge pull request #3596 from ninnypants/fix_product_result_count

Fix result count display when posts_per_page is set to -1 @coenjacobs .14
Merge pull request #3594 from markoheijnen/Fix-php5.5

Move return class after class definition. Fixes PHP 5.5 fatal errors.
Croatia is EU Fixes #3615.

@coenjacobs .14
Lock files - prevent full path disclosure. Fixes #3580.

@coenjacobs .14
Replace deprecated $wpdb::escape() with esc_sql()

Conflicts:
	admin/settings/settings-tax-rates.php