Update 1.5.1 MCP mappings

cp ~/minecraft/1.4.x/MinecraftForge/mcp/conf/joined.srg 1.5.1/obf2num.srg
py chain.py ../MinecraftForge/mcp/conf/ - | sort > 1.5.1/obf2pkgmcp.srg
py reverse-srg.py < 1.5.1/obf2pkgmcp.srg | sort > 1.5.1/pkgmcp2obf.srg
py numpkg.py < 1.5.1/obf2num.srg | sort > 1.5.1/obf2numpkg.srg
py chain.py 1.5.1/obf2numpkg.srg 1.5.1/obf2pkgmcp.srg | sort > 1.5.1/pkgmcp2numpkg.srg
py numpkg.py < 1.5.1/obf2num.srg | sort > 1.5.1/obf2numpkg.srg
py chain.py 1.5.1/obf2numpkg.srg 1.5.1/obf2pkgmcp.srg | sort > 1.5.1/pkgmcp2numpkg.srg

Forge update:
https://github.com/MinecraftForge/MinecraftForge/commit/7c6468a9ea956e743e2e8c7314808525a65e6ebc