Add Szabolcs Nagy's deflate/inflate code from git://git.suckless.org/flate

Confirmed with him on IRC it's ok to use under toybox license, glued the files
together and hammered square peg into round hole, no other changes yet.
Convert leading tabs to spaces for gzip.
More gzip whitespace tweaks, and the occasional curly bracket. No actual code changes.
gzip: alphebetize help entries and remove trailing literal \n, check for command line option groups, move len/dist tables to GLOBALS and calculate instead of including literal tables, collate enum and typedef, convert main to toybox option parsing.
Add /prefix netmask support to ifconfig, ala "ifconfig eth0 192.168.1.42/28"
Use right config for single builds.
More cleanup.html documentation, still way behind...
Tweak help text.