add link to voxel plugin to readme
add recipe for wooden planks and fix crafting bugs. closes #125
unequip works with hand as a destination. closes #126
fix incorrect INVENTORY_SLOT_COUNT.
fix not setting currentWindow to null after closing window.

fixes #106
better wording in crafting example
Release 0.0.28
add window.emptySlotCount()
merge
Merge branch 'master' of github.com:rom1504/mineflayer