Revert "Adjust the values of dirs1 and dirs2 so that rotate_and_place orients textures correctly"

This reverts commit 9878e8de4fdf232ebb77b396766c339786c01218.

See: https://github.com/minetest/minetest/issues/1939 and IRC log for discussion
Add support for NoiseParams in minetest.get_perlin() and add docs on NoiseParams to lua_api.txt
Mapgens: Rename m_emerge to prevent name collisions
LuaPerlinNoiseMap: Prevent invalid memory access when attempting to generate 3d noise with a buffer created for 2d
Fix typo in mapblock.h