FIX: Incorrect IPv6 prefix length when not /64

in getifaddr (which is used to set the nvram ipv6 variables in uhcpd), bitwise 
operations are used to calculate the last byte of the netmask on prefix lengths that 
are not multiples of 8 (see line 712). Unfortunately, these are being performed on a 
32-bit integer, not an 8-bit char. So /60 ends up becoming /84, for example.

This bug results in non-/64 block IPv6 prefixes that are delegated via DHCP-PD to be recorded incorrectly. The incorrect prefix length is recorded in nvram and used by dhcps and radvd, but the correct prefix assigned to the bridge interface remains unchanged. As a result, DNS and router advertisement are broken.

changing this function to use ffs() instead to calculate the least significant bit fixes the length calculation, and resolved this but.
Updated documentation
Removed temp files accidentally committed
Replaced with upstream patch.  Revert "miniupnpd: Enable delay after M-SEARCH requests to fix log flooding from Plex"

This reverts commit 9ad967117b51f3026d9ce0357c32f1dd578a2f5b.
Merge branch 'master' of github.com:RMerl/asuswrt-merlin
miniupnpd/minissdp.c: add a default delay before SSDP response (patch from upstream)
custom_clientlist is a permanent, not temporary var (resolves content being lost after reboot)
Bumped revision to beta 4
Merge pull request #687 from NickZ/master

FIX: Incorrect IPv6 prefix length when not /64
General documentation updates, fixes, and cleaned up changelog in preparation for the final 376.44 release
Merge branch 'master' of github.com:RMerl/asuswrt-merlin