#422. Added correct price function, price of post saved.
#422. Backmerge with master.
#422. Fixed js global price, issue with empty categories selects.
#422. Added check of affected price types, some enhancements of code.
#422 Improced documentation and method names
#422. Affected should be used only with global and category price types.
#422. Backmerge.
#422. Implemented change post price type value function.
#422. Added revenue model save on price type value modification.
#422 Improved documentation
Merge branch 'feature/422_bulk_editing_all_price_should_not_affect_all_posts' of github.com:laterpay/laterpay-wordpress-plugin into feature/422_bulk_editing_all_price_should_not_affect_all_posts

Conflicts:
	laterpay/application/Helper/Pricing.php
#422 Code formatting
#422. Remove hidden categories from bulk categories option.
Merge branch 'feature/422_bulk_editing_all_price_should_not_affect_all_posts' of github.com:laterpay/laterpay-wordpress-plugin into feature/422_bulk_editing_all_price_should_not_affect_all_posts
#422. Minor changes in code format.
Merge pull request #428 from laterpay/feature/422_bulk_editing_all_price_should_not_affect_all_posts

Feature/422 bulk editing all price should not affect all posts
Fixes #422