Fixed small resource leak on daemon quit.
Implemented zone duplicate checks with AVL.

Not so slow with large number of zones now.

refs #2174, #2204
Simplified heap for ptrs, fixed wrong pointer manipulation.

fixes #2174
Fixed typo in debug output.
Detect and disallow duplicate zone origins in config.
Fixed slave zones SOA check on startup not cancelling previous event.
Fixed broken heap_comparison and timercmp(>=) on some platforms.
Fixed small resource leak on daemon quit.
Implemented zone duplicate checks with AVL.

Not so slow with large number of zones now.

refs #2174, #2204

Conflicts:
	src/knot/conf/conf.h
Simplified heap for ptrs, fixed wrong pointer manipulation.

fixes #2174
Adding/removing RRSIGs in zone-diff.

- If there was no counterpart RRSet in other zone, RRSIGs were ignored.

Refs #2197 @2h
Added extra check to semantic checks.
Typo fixed.
Updated version and RELNOTES.
Make CLASS, TYPE converting functions thread-safe

refs #2192 4h
Correct function return type
refs #2192
Fix memory leak

refs #2192
Fix pointer comparison
Fix memory leak
Fix memory leak