implemented logging and optional termination of existence check via function_exists() on blacklisted or not whitelisted functions
Merge branch 'feature-fn-exists-log-and-terminate'

Conflicts:
	tests/executor/eval_blacklist_with_exists_forbidden_on.phpt
	tests/executor/eval_whitelist_with_exists_forbidden_on.phpt
	tests/executor/func_blacklist_with_exists_forbidden_on.phpt
	tests/executor/func_whitelist_with_exists_forbidden_on.phpt