Liquids should target block underneath when mining

[satoshinm]

Since they cannot be mined, when targeting a liquid block (lava/water), it should be ignored for block targeting and instead target the block behind it, not the infinitely hard liquid block itself:

#72 Liquids

[satoshinm]

Put another way, liquid block should be considered "transparent" for the purpose of block targeting.

Similar to https://hub.spigotmc.org/javadocs/bukkit/org/bukkit/entity/LivingEntity.html#getTargetBlock-java.util.Set-int-:

Block getTargetBlock(Set<Material> transparent,
                     int maxDistance)
Gets the block that the living entity has targeted.
Parameters:
transparent - HashSet containing all transparent block Materials (set to null for only air)

[satoshinm]

Also clouds