Shorter mipsle shell_reverse_tcp
Add formatting blank lines and delete comment
Don't use a temporary registerfor the dup2 loop counter
Add support for MIPS reverse shell staged payloads
Fluch data cache and improve documentation
Lands #2832, @jvazquez-r7's fixes to mipsel shellcode.
Land PR #2881, @jvazquez-r7's mips stagers.