added error-page management
added accepting hook
fixed fd leak in error pages
completed error pages
core/config: fix memory leak

Reported by Coverity s CID #1128441
plugins/gccgo: fix memory leak

Reported by Coverity as CID #1128440
core: Fix unintential integer overflow

The expression would be evaluated as 32bit unsigned before
promoting to 64bit unsigned so cast the strtoul return value to
avoid integer overflows. Please note that the value passed here
comes from the user.

Reported by Coverity as CID #971244.
Merge pull request #465 from xrmx/coverity2211-2

core: Fix unintentonal integer overflow
Merge pull request #464 from xrmx/coverity2211

Fix a couple of memory leaks
reverted gccgo argv_list free
remove zeromq from build profiles
prepare for 1.9.21
added hook-accepting1
added write hook
added accepting once variant
added unlink command
various fifo improvements