* rework shallalist processing: significantly reduce memory consumption
during archive extraction and merging.
* considerable reduce memory consumption during adblock source
processing.
* considerable reduce memory consumption of sort (sorts only the domain
list and not the bigger dnsmasq file)

other changes:
* auto detection/defaults for adb_if, adb_dev, adb_ntpsrv, adb_maxloop,
adb_maxtime and adb_minspace - these options can be safely removed from
previous adblock configuration file
* check total memory and main uhttpd configuration on startup
* documentation update

Signed-off-by: Dirk Brenken <dirk@brenken.org>

- centralized logging via separate function to stdout, syslog and file
- remove dependencies between helper functions
- add two new options "adb_maxtime" and "adb_maxloop"
- add description to every adblock config option (see
adblock.conf.sample)
- update README.md

Signed-off-by: Dirk Brenken <dirk@brenken.org>