ELUA_ENDIAN_* and not ALCOR_ENDIAN_*

I somehow overlooked this in SConstruct.
When you invoke Lua from the shell
without this fix, it simply crashes.

So, Alcor6L with Lua now works without
issues.
Move language specific shell commands
to the top.
Re-enable eluarpc.c

eluarpc.c does not contain any Lua specific
references. It is used by the RFS sub system.
I was able to get eluarpc.c to compile with
PicoC.

For now, eluarpc.c looks language agnostic.
Include eluarpc.h in src/shell/shell.c

This fixes the compilation issue with
BUILD_RFS in platform_conf.h