Refresh 1.5.1 release mappings

Now up-to-date with the MCP 7.44 mappings used in Forge 7.7.1.622, for
the official 1.5.1 release. Previously generated using 7.44pre2 mappings.
This is an important update with several commonly-used symbols named (textures).
Also now includes both client and server 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 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