This update is for Minecraft / Spigot 1.13 & 1.14

Mainly code improvements, but fixes issues when using standing signs. The signs used can now be wall signs or floor signs, or even a mixture of both.

Change Log:
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1) refactor block code, add blockhandler class
2) use correct import for sign blockdata
3) add method for targetting block
4) fix default out message from invalid command