Merge pull request #2 from MariuszT/master

Fix pget_virtualchest. Closes #1. Thanks MariuszT!
Clarified documentation.
Merge branch 'master' of github.com:EntityReborn/CHVirtualChests.git
Merge pull request #4 from MariuszT/master

get_virtualchest will return null if no virtual chest exists. Thanks MariusT!
Fixed test compilation failure.
Merge from 'master' https://github.com/EntityReborn/CHVirtualChests.git