Fix dead bush drops nothing

[XuZhen86]

This pull request tries to fix the bug that dead bush drops nothing when breaks.

Observed behavior: Dead bush drops nothing when breaks.

Expected behavior:

Dead bushes drop 0–2 sticks when broken without shears. When shears are used, a dead bush will drop itself. If the block below the dead bush is removed, the bush will simply disappear without dropping anything. Dead Bush

Solution: Rewrite the getDrops() in BlockDeadBush. Returns nothing when tool == null Returns the dead bush when tool is a shear, otherwise return 0-2 sticks.

[mastercoms]

Thanks for your contribution to Glowstone!

[mastercoms]

Sorry, I missed your question about a tool null check. Items should be checked if they are empty, using InventoryUtil.